But it was! It was all right. Not the following morning, which was gruesome and hangover-blighted, but one a day or two later.

I was sitting in the kitchen reaching for the ersatz marmalade-it was made with cabbage and honey-across the breakfast table when there was a knock at the door. The landlady went to see who was there. She returned with a familiar envelope marked PRIORITY PRIORITY in blue letters. in blue letters.

Through the gla.s.s of an upper window-the kitchen was in the bas.e.m.e.nt-I saw a telegram boy mount his bicycle. Serried ranks of iron railing staggered his steady start.

What he had brought was, I knew as soon as it came into my hand, a missive from Sir Peter containing my fate. It looked just the same as the one which had first summoned me to Adastral House all those months ago. Leaving the margarine soaking into my toast, and undergoing a keen perception of bad news, I opened the envelope with a trembling hand.

PROCEED WITH URGENCY TO SUPREME HEADQUARTERS ALLIED EXPEDITIONARY FORCE (SHAEF), BUSHEY PARK, TEDDINGTON, TO TAKE UP ROLE OF PERSONAL METEOROLOGICAL a.s.sISTANT TO GROUP CAPTAIN STAGG. PROCEED WITH URGENCY TO SUPREME HEADQUARTERS ALLIED EXPEDITIONARY FORCE (SHAEF), BUSHEY PARK, TEDDINGTON, TO TAKE UP ROLE OF PERSONAL METEOROLOGICAL a.s.sISTANT TO GROUP CAPTAIN STAGG.

I leaped up from the table and cheered, knocking over the counterfeit marmalade in my joy. "I've got a job,rdquo; I cried to the landlady. "I'll be leaving today."

"Good. Make sure you pay your rent," was all she said, with a sour mouth.

Once I had recovered my composure, and the marmalade jar had been rescued, I ate the rest of my breakfast in a jolly mood, certain that at last the right path had opened up for me in the tangled wood of life. I settled my account with the landlady and went upstairs to pack.

Taking the train from Waterloo to Teddington, and then a bus to Bushey-on 7 May 1944, my diary says-was rather like going home for me. I'd lived in Richmond before the war, as it was convenient for the observatory at Kew. But now it was a home I barely recognised. Southern England was loaded with troops and materiel. There was khaki everywhere. The trains were full of soldiers and the roads packed with convoys of tanks and landing craft and endless lines of lorries with canvas covers heading for the coast.

We waited in the bus for almost an hour for a lorry carrying an enormous length of concrete-I later realised it was a section of one of the 'Mulberry' artificial harbours-to manoeuvre itself round a corner. There was a lot of shouting and sounding of horns by the drivers of the backed-up vehicles.

Then it all cleared and we were on our way, pa.s.sing into a green archway of trees over the road. To me it felt a tunnel joining two segments of my life. For it was here that I resolved to stop the drinking, which had been rather building up, and knuckle down at last.

Finally, I reached Bushey. Part of the park was surrounded by high walls; the rest was cordoned off with tall fences. American Military Police with white helmets and unsmiling faces guarded the gate. As they checked my papers, I wondered again about Stagg. He had always been very good to me when I worked under him at Kew, though others found him a difficult, p.r.i.c.kly man. Later this reputation came to dominate, but people had no idea of the strain he was under. By the time I arrived at Bushey Park he had been working on the invasion forecast for several months.

It was late Sunday afternoon when I arrived, but no one would have known it from the hustle and bustle of the place. I had quite a time getting through the various security cordons, but after numerous calls by the 's...o...b..a.l.l.s' (a common nickname for the men in white helmets), I was escorted to the SHAEF meteorological office.

It was quite a long way, and as I followed one of these s...o...b..a.l.l.s through the temporary buildings-Nissen huts, cement storehouses, messes and troop quarters in tents and tin-roofed sheds-I was borne along in a flood of frenetic activity. Officers and men, British and American, from all the services, were rushing about with papers and files under their arms. The atmosphere was rather like that of a school on the day before a very important examination.

The Met section was situated in the main headquarters, a long, low-slung building-rather like a much larger version of my cot-house in Scotland, but built of concrete blocks, not stone-covered with a camouflage net. Stagg's office was next to the map room, the operational headquarters for the invasion. I thought I caught a glimpse of General Eisenhower, but I couldn't be sure.

The s...o...b..ll knocked on the door.

Three.

Stooping, Stagg appeared in the frame. Wearing a slate blue RAF group captain's uniform, he greeted me with a weary smile. "h.e.l.lo, Meadows. How are you?"

"I've been better," I replied, as the MP marched off.

"Yes. I am not surprised. Sir Peter told me all about that dreadful business in Scotland. Ryman was a great man, but it is understandable that these things happen."

"Is it?" I said doubtfully, suddenly realising that my role in Ryman's death was by now common knowledge in the meteorological community.

"Yes, in wartime it is understandable. Look, whatever happened, I'm glad you're here, Meadows. I desperately need some help. They gave me a list and I picked you."

Like Sir Peter, Stagg had aged markedly, the strain of his task accentuating the structure of his thin, severe face, the most noticeable feature of which was a light moustache. The total effect was a curious mixture of strength and weakness, strong will tempered with a sense of anguish.

"Well, sir, that is why I am here," I said, looking at his uniform. "And I will do what I can. I see you have become a military man."

"Ah yes. I want to talk to you about that. You'd better come in."

He led me into the office and shut the door. It was a large, spa.r.s.ely furnished room with a dark brown carpet. There were weather charts on the walls and a big table in the centre, with three telephones standing on it: one red, one black, one white.

Stagg sat at a small desk, motioning me to one of the chairs at the table. "I'm afraid you'll have to join up, too," he said. "I was having a lot of problems with chaps not taking me seriously as a civilian, so the Air Ministry finally mobilised me. Our allies don't like to deal with civilians when such highly secret matters as these are being discussed. For a time I was demoted and my deputy, Colonel Yates of the US Air Force, became chief Met adviser. The American generals were not happy that a civilian should come between them and Yates. They like to have a clear chain of military command. You'll meet Yates soon. Nice fellow. Now, sit back and I'll tell you how it is."

Looking at me over a pile of dossiers on his desk, Stagg explained that, since the middle of April, he and a team of forecasters had been producing a five-day forecast every Sunday evening for distribution to General Eisenhower and the rest of SHAEF. It related to the crossing of the English Channel in order that the Allies gain a foothold on mainland Europe-which first step to recovery of the continent was code-named Operation Neptune. The invasion as a whole was code-named Overlord.

"The forecast is for the whole week," Stagg said. "Every Thursday is regarded as a dummy D-Day, which is the name we are giving to the invasion date. H-Hour, similarly, is the landing time for the first airborne troops. As you've probably gathered from the number of troops moving about the country, it is likely to happen quite soon."

He spoke in a low tone. "I can't tell you how difficult this is, Meadows. I need you to help me with the technical work, including taking the minutes and preparing doc.u.ments for each conference. Representatives of the three armed services have been trying to foresee each critical weather element for D-Day by convening a conference. I need you to examine the forecasting process."

"What are the critical elements?" I asked, trying to focus my mind.

"Broadly, the limiting conditions are as follows." He counted them off on the fingers of his left hand.

"(A) D-Day should be within one day before to four days after a full moon. (B) There must be quiet weather on the day and for three days afterwards. Wind to be of no more than force three onsh.o.r.e and force four offsh.o.r.e. (C) Cloud to be less than three-tenths cover below eight thousand feet; visibility three miles plus. Or as an alternative to condition (C): (D) in which case the cloud base itself has got to be above three thousand feet generally, morning mist not excluded. There are other constraints affecting parachute drops, which we have not yet tried on this scale."

I was shocked that such a grand, important plan as Overlord depended on conditions so difficult to fulfil. No wonder Sir Peter was anxious. "It doesn't sound very likely in any of those permutations," I ventured.

"No," Stagg replied lugubriously. "That is why it's such a devil. But it must be possible. It has to be, for all our sakes. The immediate military objective is to land a force on a fifty-mile strip of enemy-held coastline. A force strong enough, and with supply lines secure enough, to resist quick dislodgement. We need moonlight and we need low tide, but the critical probabilities will be the state of the sea, which of course is mainly dependent on the wind strength on the beaches, and the amount of cloud."

He scrabbled around for a piece of paper. "Look at this b.l.o.o.d.y thing."

Typed out, bearing the stamp BIGOT, the paper listed the probabilities of various combinations of the conditions Stagg had outlined, expressing them as racing odds:

LIMITS.

CHANCES CHANCES.

TO ONE TO ONE.

AGAINST AGAINST.

MAY MAY.

JUNE JUNE.

JULY JULY.

I: WANING MOON.

B AND D WITHOUT A.

4 4.

2 2.

5 5.

B AND C WITHOUT A.

9 9.

4.5 4.5.

19 19.

II: WITH NEW OR FULL MOON.

B AND D WITH A.

11 11.

6 6.

16 16.

B AND C WITH A.

24 24.

13 13.

50 50.

III: FULL MOON ONLY.

B AND D WITH A.

24 24.

13 13.

33 33.

B AND C WITH A.

49 49.

24 24.

100 100.

The word BIGOT, I would discover, was stamped on all Overlord doc.u.ments. The rationale was that no one would go about boasting that they were reading papers with the cla.s.sification BIGOT, any more than they would say they only had one t.e.s.t.i.c.l.e.

"Crikey," I said, doing some quick calculations in my head.

"Exactly," said Stagg. "Not the best conditions in which to undertake the greatest amphibious operation in history."

He took off his gla.s.ses and rubbed his eyes. "It's all much riskier once you put in the demand for moonlight. Odds in category II are roughly three times those in I."

I was puzzled. Surely it would be best to invade under cover of darkness. "Why do you need the moon?"