"I'm sorry, but I still don't get it," said Stagg beside me, his feet crunching on the gravel.

"The Ryman number tells you how turbulent a parcel of atmosphere is. The reason Sir Peter sent me to Scotland was to find how wide or tall is that parcel of atmosphere-the range of a given number, as it were. The importance of the WANTAC ship is that its readings may show evidence of the small high pressure interval Eisenhower needs. If it is, end of story."

"I should get some sleep, if I were you; we're not yet at the end of any story," Stagg said curtly.

We were at the edge of the lawn. I kicked the turf with the toe of my shoe.

"Which reminds me," Stagg continued. "There's something I have forgotten to tell you. Air Marshal Tedder came up to me after the meeting and said we-I mean the British-ought to put some meteorologists in with the invasion force to take measurements and check how close our forecasts are to the reality on the ground. Apparently the Yanks have two whole squadrons of battlefield weathermen. We've run plain out. Tedder spoke to Sir Peter and he rang me, wondering, since you are young and fit and know what we have been up against here, whether you'd like to go in with them? He said he thought it might be a way for you to make amends for that business with Ryman."

"Did he now?" I instinctively wanted to say no, but instead asked for some time to think it over. In some ways it was an honour to be asked-but I had no military training whatsoever. Feeling exhausted, and overwhelmed by the gravity of the situation, I stared up into the night sky. The stars seemed to shudder, as if feeling the same apprehension.

"I am not a soldier," I said, as we turned to go back to the house, whose serried windows showed tiny lines of light-not visible from above-at the edges of the blackout blinds.

"That is a drawback," said Stagg. "But it would be tremendously helpful if someone who was actually involved could compare theoretical forecasts with actuality. Think about it, anyway, as even if we postpone today we are going to have to go in the next three weeks, come what may."

He gave a bitter laugh. "Come what June! Come on, we'd better get back."

On our way back to the main house-as we approached that great Victorian lump-we heard heavy running footsteps on the gravel and soon met an out-of-breath General Bull, who said he had been looking for us.

"Don't disappear like that! I've come to tell you, Monday may well be put off. If so, we are back at D minus three again as of today."

This meant the a.s.sault would be on Tuesday, but it wasn't quite as simple as that. "Because of your forecasts, General Eisenhower is thinking of holding up D-Day on a provisional, hour-by-hour, day-by-day basis," Bull continued. "We'll meet at four fifteen tomorrow morning and, depending on what you have to say, the supreme commander will confirm the postponement or not. If appropriate, he will then, or later in the day, decide definitely whether Tuesday will be D-Day."

It appeared provisional, from the way Bull was talking, but really that was it. Between us, Stagg and I, Krick, Petterssen, Douglas and the Admiralty, in conjunction with thousands of other Allied meteorological staff, had finally caused a decision to be made. It seemed like Ryman's forecast factory had come true-but for all that we still weren't sure whether the decision to postpone would be the right one. The sky was practically clear; there was no rain.

"Maybe it is madness to send you on a wild goose chase into France under these circ.u.mstances," said Stagg, once Bull had gone.

"No," I said. "I'll go."

A strange feeling had come over me in the general's presence. Shaking off my anxiety and tiredness, I suddenly desperately wanted a shot of the action. I wanted to be among the ranks of men whose fates our forecast would determine. I had spent too long among figures of the mathematical type.

But I still had one last set of calculations to make. It was time that everything I had worked for was met directly. This meant facing up to the forecast problems with a new purpose-fulness-acting on what I had learned from Ryman and from the experiment I had conducted at Saunders-Roe, and gaining new meaning and new strength from the conviction that Gill's gift of the sh.e.l.l cases had supplied.

So I went, that Sat.u.r.day night, back up to the Nissen hut and began applying the Ryman number to adjacent parcels of atmosphere, all the way from WANTAC near Iceland down to the Channel, using the simulation method Gill had suggested. I was not entirely confident, but I had to try. It seemed to make sense: because it allowed a measure of uncertainty into the calculation, this method was the best way to future-proof the forecast.

I needed to inoculate against my dizziness, uncertainty in general as it effectively was, but were the sh.e.l.l cases and their contents really the medicine? They seemed in one light like another type of dizziness in themselves, but maybe that was the point. What the Africans did, in Zomba after the slide, was allow themselves to be bitten by whirligig beetles. The beetles were collected from mountain rivers and pools and held to the breast near the nipple where they bit in a defensive reaction, releasing a powerful steroid.

So the kizunguzungu kizunguzungu epidemic ended. epidemic ended.

Four.

In the early hours of Sunday 4 June, with the 3 AM AM conference over, I was working bleary-eyed on my equations in the hut on the bluff. Outside, the sentry stirred and the Channel fretted against the boundary sh.o.r.e. The far-called navy was melting towards the battle line, pushing forth tentatively, like the shy anemone, unlocked at on its ocean bed. In France, on the moon-blanched land, waves turned, foam fell, whiting more the sepulchre. Meanwhile on each page, as I was writing, the figures seemed to move. These are the images that return. conference over, I was working bleary-eyed on my equations in the hut on the bluff. Outside, the sentry stirred and the Channel fretted against the boundary sh.o.r.e. The far-called navy was melting towards the battle line, pushing forth tentatively, like the shy anemone, unlocked at on its ocean bed. In France, on the moon-blanched land, waves turned, foam fell, whiting more the sepulchre. Meanwhile on each page, as I was writing, the figures seemed to move. These are the images that return.

An hour or so later Stagg would attend the first of what turned out to be two crucial commanders' conferences in the library at Southwick. At the first meeting, even though the weather was still fine, Stagg told them he thought it could go bad on Monday, with wind and cloud appearing in four or five hours' time. Eisenhower confirmed the previous evening's tentative decision to postpone.

Everything was in the balance, we were indeed not yet at the end of the story. We seemed to be stuck in the middle of the end, waiting for the variables to come into alignment.

I tried not to become frozen in the terrible immobility that this provisionality can entail. Smoking heavily, I continued with my calculations, pen in one hand, cigarette in the other, sh.e.l.l cases and numbers on the table in front of me. I knew I needed to have patience-as every silent sheet could be the one that bore fruit. But first a tree had to grow, hurrying its rivulets of roots and fibres, each one a boundary for the next, across the waiting page. An equation tree, glowing and strong.

It wasn't easy. At one point I knocked one of the sh.e.l.l cases off the table and had to scrabble around on the floor picking up the precious numbers. This meant I had to start all over again, just in case I had lost one of the numbers. Extremely tense, feeling as if iron hooks were being inserted into my shoulders, I decided the best thing would be to go for a walk. Stiff from sitting for so long, I hobbled down the hill into the woods, until I came to the pond.

The rowing boat which Stagg had kicked was still moored to its jetty. Dispersed through the branches and leaves of surrounding trees the moonlight was shining, honeycombing the wine-dark water and the ribbed sh.e.l.l of the boat's interior. It was still a gloomy place, hooded with melancholy, but now it was a beautiful gloom.

From among the trees' black bars an owl hooted, making the air tremor. On an impulse I climbed into the boat. Having released the painter, I picked up the oars and began to row round that moon-dappled pond. With each stroke, as I leaned into the resisting water, the tension went out of my shoulders, and the mental exhaustion-like muscle pain in the brain-started to lift.

With each circuit of the pond, it was as if I was making a tour d'horizon tour d'horizon of the workmanship of turbulence, not just in the zones of air and water, where vapour is lifted by the sun from oceans, lakes and rivers and diversely distributed by the wind, but the uncertain edges, where curls of mixing gas give meaning to the idea of s.p.a.ce. of the workmanship of turbulence, not just in the zones of air and water, where vapour is lifted by the sun from oceans, lakes and rivers and diversely distributed by the wind, but the uncertain edges, where curls of mixing gas give meaning to the idea of s.p.a.ce.

The boat shivered. I became undecided again. Once you leap the limits and start on further considerations you begin wondering-since the earth is just a little p.r.i.c.k in s.p.a.ce compared with the galaxy, never mind the whole-where it is all going to end.

I righted the skew.

The sound of the blades dipping in and out of the water together with the rattle of the rowlocks was like music accompanying the slow song of my thoughts. Even though I was conscious that I was sitting on the cross-plank of a rowing boat, pulling myself from eddy to eddy, it was as if I were elsewhere, seeing myself from above as I made my circuits. As I might appear to the tree-perched owl. Or from below, among the myriad mansions of submerged bacterial life. Or from the side, where a moorhen anxiously called each time I pa.s.sed. Or that distant rift on Venus, from within whose folds a quite alien species might watch.

I listened. Gradually, like the appearance of a new sh.o.r.eline, the realisation came upon me that to see the pond I was circ.u.mnavigating as a gloomy place, or even as a beautiful gloomy place, was to impose on it as Europeans had imposed upon Africa. As my family had imposed on Africa. As I had myself. Trying to make the world speak in human terms alone was akin to making Cecilia and Gideon speak the kitchen-Kaffir English we foisted upon them.

Somehow or other I had to learn to see the limit-rich, frame-filled world as one without without limits, limits, without without frames-see it, feel it, speak it in that other language of turbulence which was itself differential from the start. Promiscuous of perspective, it was less liable to the drag of bias and error. Could this programme have any place in the canon of the physical sciences? Surely that was a vain ambition. frames-see it, feel it, speak it in that other language of turbulence which was itself differential from the start. Promiscuous of perspective, it was less liable to the drag of bias and error. Could this programme have any place in the canon of the physical sciences? Surely that was a vain ambition.

Science is not about 'feelings'. But nor, at least at the highest level, is it the reductionist activity it is commonly supposed to be. Great scientists use their imagination, they feel their way towards a theory, then seek to prove it. With turbulence, exactly because of its intermittency and mutability, I realised that night that this 'feeling towards' was actually key. Extrapolating from immediate immediate connections, we have to keep an idea of connections, we have to keep an idea of all all connections hovering before us, as an ideal insight into the whole. Because the whole cannot be reached, we can grasp it only by intuition-by chasing not the specifics but the beautiful ghost of an idea. connections hovering before us, as an ideal insight into the whole. Because the whole cannot be reached, we can grasp it only by intuition-by chasing not the specifics but the beautiful ghost of an idea.

Once this thought had rushed in on me, others came, relating directly to the modal variety I ought to employ in calculating the forecast. I would have to keep shifting between Ryman's, Krick's, Douglas's and Petterssen's methods to get the required promiscuity of perspective. Effectively this was what we had been doing, but no one had tried to turn the to-and-fro of the conferences into an active programme.

Exhilarated, I returned to the hut with new vigour. My hand moved quickly under the desk lamp, covering the blank sheets. I solved calculation after calculation, working methodically forward through the charts, through tomorrow to expected conditions on Tuesday.

Sitting south of Iceland, on the eastern flank of a major deepening low south of Greenland, was a small parcel of warm air thrown up by the motion of the main surface low. It was this parcel that WANTAC had been reporting. By about 8.30 AM AM tomorrow, I calculated, the Atlantic parcel would develop into a higher-pressure ridge at 300 mb. Within an hour and a half the ridge would intensify at 500 mb. It was heading east, at a rate fast enough to cause, from early on Tuesday morning, a small temporary block in the Channel from the prevailing bad weather. There would be rough seas, heavy rain and gale-force winds later on Monday, but after that (I was as sure of it as I have ever been of anything) would come an invasion-friendly haven: a brief time of immunity from storms. tomorrow, I calculated, the Atlantic parcel would develop into a higher-pressure ridge at 300 mb. Within an hour and a half the ridge would intensify at 500 mb. It was heading east, at a rate fast enough to cause, from early on Tuesday morning, a small temporary block in the Channel from the prevailing bad weather. There would be rough seas, heavy rain and gale-force winds later on Monday, but after that (I was as sure of it as I have ever been of anything) would come an invasion-friendly haven: a brief time of immunity from storms.

Perhaps only a mathematician can understand how suddenly the treasure can come. It is as if a key has been deftly turned and a casket sprung open, revealing contents within more precious than could be thought possible.

I stared at the lamp. At the paper. At the lamp. The filament of the electric light burned in its bulb, like the sun filling an arch of sky. The filigree of black figures grew, rising against the white sheet. It was as if they were the rigging of a ship setting forth on a voyage of validation, a voyage in which vessel and sail carried on into the future, somehow leaving the spars of mast and yards behind.

My tree.

That was what was left onsh.o.r.e.

My equation tree.

Night decayed, morning came, the sentries changed their station. A beam of dawn light descended through the hut window, beating rose-red on the page. Did the tree promise forgiveness? For killing Ryman, hanged from his balloon, arms collapsed? For damaging Gill, stranded widowed and childless in Seaview? For making myself a monomaniac, subject to an idea of change and flux that actually fixed me like a b.u.t.terfly on a pin?

I could not say 'yes' to any of these. But in that moment, which seemed to win to my side both chaos and and order, I think I came close to an ideal of life. Recognising its mutability, I experienced a moment of freedom. order, I think I came close to an ideal of life. Recognising its mutability, I experienced a moment of freedom.

As for the final calculation, it's hard to explain: you just know know it is right. Ryman was a big reason why. What he had taught me, I realised then, was the importance of intermittency. Not just scientific intermittency, but mental and emotional intermittency, too. How, in a world of disintegration and endless renewal-a continuum, a world of flow-one must find one's own rhythm exactly by recognising the incompleteness of the melody. it is right. Ryman was a big reason why. What he had taught me, I realised then, was the importance of intermittency. Not just scientific intermittency, but mental and emotional intermittency, too. How, in a world of disintegration and endless renewal-a continuum, a world of flow-one must find one's own rhythm exactly by recognising the incompleteness of the melody.

It was a great gift, because incompleteness is what points to that ideal of the whole. It shows the way to whatever is emergent at the limits of any system, from an ant-lion's nest in Nyasaland to the ever-expanding edges of the universe.

I sat for some time with the full calculation of the Ryman numbers for all the adjoining areas of weather between Iceland and the Channel in front of me-along with the lamp, the piles of bra.s.s numbers relating to each quadrant, and the sh.e.l.l cases standing like statues on the table. Looking behind at every step was like peering into a dream of becoming-watching something inspire, move, breathe, awaken...

There was a danger in savouring the showing of the thing like this, I knew that. I was cautious of ecstasy, but the highest branch of the tree-G.o.d's mercy! what a stroke was there. It was not just the one forecast I saw emanating from that twig-tip but something larger, something more glorious. The jubilant intimation of a new era in meteorology, affecting not just D-Day but the whole empire of the atmosphere.

I looked at my watch. It was 9.05 AM AM and I was starving. and I was starving.

With a whoop of triumph I grabbed the papers on which I had done the sums and burst out of the hut, startling the new sentry, who was already dozing. I laughed into the brightening air, took a gust of it into my lungs, then ran down the hill to the main house. On the gravel outside, Don Yates was consoling Stagg about the non-arrival of the bad weather which had caused the postponement of the next day's plans. They were quite oblivious to my revelation, still worrying about the bad weather in which I believed I had spotted a future c.h.i.n.k.

"We're in a wood, chum. We're sheltered from the wind and a cold front has definitely been measured in Ireland," Yates was saying, rubbing the dark hair on the top of his head. The Irish cold front confirmed that the decision to postpone had indeed been correct.

"Anyway, look!" Yates's hand extended into the air. Stagg and I followed the American's pointing ringer. I was breathing hard from running down the hill.

Sure enough, in the west the tree tops were swaying. Wind was bearing cloud along in threatening armadas. The clouds were of the heaped, turreted, galleonish type that often spells thunderstorms. Altoc.u.mulus castellatus. "But it sure feels weird to be celebrating a non-invasion, however successful the forecast," Yates continued.

"Better safe than sorry," Stagg said.

"It's going to be all right," I said, breathlessly. "I've found it!"

"Found what?" said Stagg crossly.

"There will will be an intermezzo. I finally worked out the Ryman numbers down from WANTAC to the Channel. It be an intermezzo. I finally worked out the Ryman numbers down from WANTAC to the Channel. It is is going to be a very stormy night, and the bad weather will continue through to Monday morning. Nothing can stop that cold front coming through now, but it will be followed by a short s.p.a.ce of more settled weather. And that means, once the cold front has pa.s.sed through the Channel, that we will be clear for an invasion on Tuesday." going to be a very stormy night, and the bad weather will continue through to Monday morning. Nothing can stop that cold front coming through now, but it will be followed by a short s.p.a.ce of more settled weather. And that means, once the cold front has pa.s.sed through the Channel, that we will be clear for an invasion on Tuesday."

I wanted to tell them how I had come to my conclusion by deliberately subduing the complete mathematics in the way Gill had suggested, and allowing in a simulation of randomness. I wanted to tell them that it was all to do with thin layers between adjacent weather systems, just as Ryman had said. But neither of them was interested in the theory.

So I explained in more detail that WANTAC, which Stagg and the others had lost faith in, was in fact the key. Its apparently discontinuous data (discontinuous with the context) was in fact a sign of a small-scale, good-weather pattern within the large-scale and extraordinary bad-weather pattern. It didn't mean Krick's generalised optimism was right-the worst summer storm series in twenty years was about to whip the Channel and would continue to do so for a day-but it meant we had a chance.

"There will be a gap," I said. "I'm certain there will be an opening. WANTAC isn't wrong, it is just reporting a movement on a different scale to those we were focusing on. If the Germans see only the main depression and not the high ridge on its flank, then we will actually have a tactical advantage. Our counterparts will see only the general panorama of bad weather, not the interval in it."

At the end of my speech I didn't get quite the heroic reception I was hoping for. Stagg looked uncertain after listening to what I had to say, but Yates's face broke into a grin. "I hope you're right. C'mon, let's go eat."

Over breakfast we heard that Allied troops had begun to enter Rome. It would be the first European capital to be prised back from the n.a.z.is, but it did not stay long in our minds. We were all thinking about the D-Day a.s.sault. I confirmed to Yates and Stagg that I wanted to go in with the American weathermen as had been suggested. I told them I was sick of sitting with the telephone at my ear and that, meteorologically as well as personally speaking, it indeed would be interesting to see how local weather related to the synoptic forecasts for large areas that we had been doing.

"Maybe not interesting enough to get killed for," drawled Yates, who was the closest thing to a man of action among us.

"You're absolutely sure?" said Stagg. "You should feel no compulsion."

"I am sure," I said confidently. "I want to see for myself whether my theory is right. The ratio I worked out, the Ryman number, it's what Sir Peter sent me to find in Scotland. And I think I have, by applying a strange avoidance of elaboration. I want to see the results for real."

Yates said he would arrange for a car to take me up to join the American Weather Squadron, which was waiting for the off in Berkshire.

As soon as we had eaten we went to the hut and pored over the latest charts for a few hours. During this time, to everyone's relief, the sky became overcast. In a few hours it would start to rain heavily. Then we had the Sunday morning telephone conference during which Dunstable and Widewing argued as normal.

Holzman and Krick thought a surge of high pressure, a.s.sociated with but separate from my minor WANTAC high, would protect the Channel. Petterssen was concerned about the rapid evolution of the second storm-Storm E-in the Atlantic; but he now thought it might not come to us as quickly as he had previously antic.i.p.ated. The Admiralty concurred.

I told people about my work with the WANTAC gauges and my positive att.i.tude fed into the discussion, with hearty support from the American contingent. I think this, apart from getting the telephone conferences together physically, was where I made my contribution to it all. It was partly just a question of language, of conviction conviction, of getting people to believe the story you were telling. Even the words you choose to represent such things can make a difference. What is the difference between 'a reasonable possibility', 'the nearest we can get to a certainty in these conditions', and 'unsafe but feasible'?

This is the marginal area we were in, reflecting the extreme complexity and rarity of the weather as set against that of a more typical June. The essential general point, which people never seem to grasp, is that volatility has a direct effect on predictability itself, as well as on whatever it is you are predicting; or (another way of putting it), don't expect the same level of predictability all the time.

This is a mistake often made by those who speculate in stocks and shares, but in fact its relevance is to the whole range of human activity: why, having been thrown into life in the first place and when everything else is so variable, should we expect predictability, of all things, to dance at an even tempo? It is just a smooth dream of comfort that life's roughnesses should yield themselves up with eyes of meek surrender like that. All the same, it is hard to live without such illusions.

I personally supported Krick and Holzman in being more forthright. There was was a slot coming, of a day or two, which presented conditions that were tolerable for the operation. The Admiralty's sea forecasts matched this a.n.a.lysis. Petterssen and Douglas, on the other hand, still harboured doubts, though it would be a distortion to say they advised 'don't go on Tuesday'. It was a matter of emphasis. They fell into line with the others, predicting clear weather for bombing and 'just about' tolerable conditions on the beaches. Technically their reservations related mainly to the further outlook after 6 June, and in this they would prove to be justified. a slot coming, of a day or two, which presented conditions that were tolerable for the operation. The Admiralty's sea forecasts matched this a.n.a.lysis. Petterssen and Douglas, on the other hand, still harboured doubts, though it would be a distortion to say they advised 'don't go on Tuesday'. It was a matter of emphasis. They fell into line with the others, predicting clear weather for bombing and 'just about' tolerable conditions on the beaches. Technically their reservations related mainly to the further outlook after 6 June, and in this they would prove to be justified.

So, anyway, Stagg and Yates went off to Eisenhower and told him they thought a fair interval would become possible from early on Tuesday morning.

The compatibility between the forecasters hardened later on Sunday, at least for a while. I myself missed the moment when peace broke out among them, leaving in the car Yates had ordered for me.

There was just enough time for me to gather some belongings and to make some further brief points to Stagg about WANTAC, which I thought he should communicate to the supreme commander. Next minute I was b.u.mping along in a khaki Packard towards Newbury, which was one of the marshalling stations for airborne troops.

The sky was darkening, it was raining heavily, and a gale was beginning to blow-but I was smiling as I was driven along. Thousands of men whose lives depended on our forecasts had been saved from catastrophe by the postponement. Soon there would be force 5 or 6 winds on the Normandy beaches and complete low cloud cover, preventing aerial bombardment or the landing of gliders and paratroops. It would have been a complete disaster; and in making the right forecast, notwithstanding the hedged-about manner in which it came, we had turned away a calamity.

My confidence about the WANTAC signals did lessen slightly in the car, I must concede. Whether the fair interval we hoped for would actually now develop on Tuesday remained to be seen. Even if it did, the conditions would be far from the minima set out on the BIGOT sheet. Moreover, other large, unpredictable depressions were wheeling across the Atlantic. At least that meant that the Germans, observing the rough seas and strong winds now ripping across the Channel, would decrease their invasion reconnaissance...

I sped along against a southward flow of heavy military traffic. The storm battered the windows of the Packard, which were filled with successive, half-glimpsed images of military transports, all dipped headlights, angles of metal, camouflage nets. Embouched for a moment among vehicles, I glimpsed a tank commander looking for a reason for the hold-up. Rain-lashed, he stood upright in his turret, moving from one side to the other to get a better view. Poking out of soaked camouflaged sleeves, his white hands gripped the edge of the hatch.

Yates said he had arranged for me to go in a glider. I didn't like the sound of that very much, but I supposed it was better than taking my chance on a landing craft. I hated the idea of drowning. Some of the poor b.u.g.g.e.rs would have to drive jeeps off the landing craft into five feet of water. I'd seen them down in Portsmouth, dipping their hands into vast drums filled with a compound of grease, lime and asbestos fibres and coating the points and distributor with it under the bonnet, then driving down the harbour slipways into the water to practise. These jeeps had upright exhausts, like snorkels. All you could see as they moved along was the vertical protrusion of the exhaust, with its little flapper-cap going like billy-o, and the head and shoulders of the driver.

I had felt like that until very recently-as if I was just keeping my head above water. Now I was stronger, I thought, as the traffic whistled on the wet road. What I had learned, apart from the proof itself, and it was simultaneous and coterminous with it, was that all things are ephemeral, although connected by a web of marvellous affinity...one that stretches from the bounds of universe to those of individual being. How wonderful it would be to be some kind of scientific superhero, able to fly without let from one misty region to the next!

We pa.s.sed a sign for Chobham, I think it was (the lashing rain made it hard to see), and I remember it was at more or less that moment that my conviction of total connectedness suffered a blow, as I saw the continuity between me and all the thugs and monsters of whom Hitler was simply then the most prominent. But looking back now, with sharpened eyes, I see the link to the maniacs is simply one of the facts that any system must legitimately ignore. At least, it must if it is to preserve its ident.i.ty.

How rarely we see it, the full picture. Through our fogged perceptions and illusions of control, how rare is that man or woman who can stay still in the strange land of dissolving elements, constant change and unpredictable fortune that is called life; can stay still long enough to perceive an ideal of the whole. And, in becoming still, become aware of his or her own flow: the buried stream of a genuine self, murmuring quietly as it winds its course. Only another's eyes can show the way to this place, and those have now been closed to me. What's left is not the ghostly aspect of her, but that of myself-of my own former inwardness that now follows me round like a strange dog.

If, tracking me down, that figment of my past were to ask me how to tell the future, I would advise it to look for patterns within systems and perturbations at their edges. Spy out what is new and-often more important-what is disappearing. Variations of input count for a lot, as does the speed at which a system operates and at which information propagates through it. When there's a big difference between those two speeds, a shock-wave can result. Ideally, information should pa.s.s through a system at a rate which allows that system to adjust to it.

That is what we have learned. That is the news from the future, conveyed through a fountain pen to a former self, as if the pen itself were a torpedo shot into the past from the bows of the ice ship. That is what I'd tell that persistent old dog of my young self, as he moseyed his way through wartime traffic to an uncertain fate, unknowing of the love and the loss which lay before him, unaware that he was hovering between Africa then and Africa now, where he might seek the plain where his old life rose.

By 9:30 PM PM I was at Newbury among the men of the 82 I was at Newbury among the men of the 82nd US Airborne Division, being taken through line after line of bulky young paratroopers. Some were dozing with their packs on their backs, their faces smeared with camouflage cream; others were sitting up alert, their expressions filled with anxiety by the great undertaking. US Airborne Division, being taken through line after line of bulky young paratroopers. Some were dozing with their packs on their backs, their faces smeared with camouflage cream; others were sitting up alert, their expressions filled with anxiety by the great undertaking.

I was introduced to Colonel Tommy Moorman, head of the 21st Weather Squadron, who were going in with the 82 Weather Squadron, who were going in with the 82nd. He a.s.signed me to Corporal Eugene Jourdaine, a thickset, round-shouldered man with bushy black hairs protruding from his nostrils.

I was to act as Met liaison between the British and Americans, but since I did not have any RAF battledress, they let me wear Weather Squadron uniform. It had a motto on the shoulder, Coela Bellatores Coela Bellatores -'weather warriors'-which pleased me greatly. -'weather warriors'-which pleased me greatly.

I was amazed at the scale of the US Army's weather operation. There were more than a thousand men in the list and another squadron, the 18th, of about the same number. But it was the US Army-issue camp-bed, one of that country's greatest inventions, which impressed me most. I got some sleep that night, more than I had had for ages, conscience for once forgetting to worm its way into my head.

Five.

On the morning of Monday, 5 June, after a hot shower-this aspect of American technical excellence also delighted me-and a breakfast of eggs, bacon and waffles, washed down with black coffee, I telephoned Stagg at Southwick. Through that by now very familiar conveyance (so familiar I had developed a skin complaint in the cup of my ear), I learned of the extremely tense atmosphere of the previous night's forecast presentation, during which Eisenhower and his battlefield commanders in the library at Southwick House had quizzed Stagg on the interval signalled by WANTAC.

As heavy rain poured down outside and wind battered the shutters, Stagg had told them that by the early hours on Tuesday, he believed wind, sea, cloud and visibility conditions would all be tolerable enough to mount an invasion. The cold front which had brought the rain was now moving south-eastwards and would clear the invasion site within two or three hours, Stagg said, and there would now be a weather window of one to two days.

Tedder asked Stagg how much confidence he had in this forecast.

"A lot," said Stagg simply. I knew what a relief it must have been for him to say those words, and after all that had happened in the past six months it gave me pleasure to hear them, too.