'Let's just take this one step at a time. We'll get everything sorted fair and square. I'm perfectly willing to provide for you and the kids. I'll be truly generous, no worries, but you know I've lost a lot of money because of the recession. Things will pick up once I get the new album launched'

'There isn't going to be a new album! Your career's over, you wizened old fool. You're just a laughing stock now,' Mum shouts.

'Right, that's it. I'm not hanging about to be insulted. Come on, kids. Never mind your stuff, we can always buy you new clothes. We're going.'

'Oh no you're not! There's guys with cameras outside. What will it look like, you dragging three screaming kids away from their mother you with your Mr Nice Guy Family Man image nowadays. What would your precious Rose-May say to that?'

'Look, Suzy, grow up. What's the point of making this so ugly? See what you're doing to the kids? You'd better watch it. You've clearly had a drink or two or ten. If you don't clean up your act you'll find I'll fight you for custody of the kids. I've got myself a very good lawyer. You'd better start cooperating. The kids are coming with me now, and if you have hysterics in front of the paps you'll simply be helping my case. I'll bring them back tomorrow afternoon. Come on now, kids.'

He lifts Sweetie in one arm, Ace in the other, and starts walking.

'Don't you go too, Sunset,' Mum says, hanging onto me.

I hover helplessly, not knowing what to do. My heart's pounding and I feel sick. Mum's asked me to stay, she needs me but Sweetie and Ace need me too. Dad doesn't have a clue how to look after children. They won't be able to manage without me.

'I'll have to go, Mum. Don't worry, I'll look after Sweetie and Ace,' I say. 'I'm not taking sides, I love you both. Please don't be cross with me, Mum . . .'

But she turns away from me and won't say goodbye to any of us, not even Sweetie.

Then we're bundled into the back of the car and we hurtle out of the gates, Dad telling us to duck down. He laughs as he speeds away, waving his cowboy hat and then plonking it on Lizzi Big Mouth's head. She laughs with him and then looks round at us.

'Hey, kids!' she says, waving her fingers in the air.

We stare at her. We don't wave back.

'Who are you?' Sweetie asks indistinctly, her thumb in her mouth.

'I'm Lizzi, sweetheart. I'm your dad's girlfriend,' she says.

'I'm Sweetie, not sweetheart. And I'm Daddy's girlfriend,' says Sweetie.

Dad roars with laughter. Lizzi Big Mouth laughs too, her horrible lips wide open, as if she could swallow us up in one gulp.

'You're my little sweetheart, Sweetie. Liz can be my big one,' says Dad.

'What about Sunset?' says Sweetie. 'She's your big girl, not her.'

'Oi, little Miss Sulky Chops, I'm not her, I'm Lizzi,' she says. She pulls a face at Sweetie, then raises her eyebrows at me.

'Hi, Sunset. You were very kind to my little niece unlike some members of your family. Thanks for giving her that panda. It was sweet of you.'

I don't want her to feel I'm sweet. I don't reply. I hold Sweetie's hand and Ace's grubby paw in solidarity. Ace shuffles nearer to me.

'I don't like her,' he whispers, not quietly enough.

I don't either, I mouth.

'I'm Tigerman and I'm going to bite her,' he says. Then he looks down at himself, stricken. 'I want my Tigerman costume!'

'Oh, Dad, Ace needs his Tigerman outfit. He'll never settle without it. Can we go back for it?' I say.

'Don't be silly, Sunset.'

'But it'll only take five minutes'

'I'm not going through all that palaver with the paps and your mother screaming her head off. I've told you, we'll stop off somewhere and buy you all new clothes, OK? And stop taking that tone with Liz, all of you. I want you to be very, very nice to her, because she's a very, very nice girl, OK?'

Of course it isn't OK. She's not the slightest bit nice. She's stolen our dad and she doesn't seem to care. Ace starts crying and Sweetie starts fidgeting. I hope she's not going to wet herself again. I'm starting to feel horribly sick. One way or another it seems likely we're going to make a mess of Dad's upholstery.

He drives us to Harrods again, trying to turn it into a treat. At least we can all go to the bathroom. Lizzi Big Mouth comes into the ladies' with us. She doesn't try to supervise Ace or Sweetie. She just stares at herself in the mirror and applies another shiny dark coat of lipstick to her big mouth.

'You wear too much lipstick,' says Sweetie.

'That's your opinion but you're just a silly little girl,' says Big Mouth.

'I'll tell Daddy you said that,' says Sweetie.

'Tell away, darling. See if I care,' she says.

She's so sure of herself. She doesn't even flatter Dad when she's with him. She just shrugs when he asks her to help us find new clothes, and says, 'I don't know what little kids like. You kit them out. It was your idea to have them with us for the weekend.'

Dad calls an assistant over quickly and Lizzi wanders off humming, messing around with the clothes on the rails, not the slightest bit interested.

Sweetie perks up now and starts to organize a new top and trousers and frilly nightie for herself, and then decides she simply has to have some little suede boots with heels. They don't make them as small as Sweetie's size but she wants them anyway, saying she'll stuff socks in the toes.

I know what I want too. It's easy: a new black T-shirt, black jeans and even new lacy mittens because the first ones are starting to tear. I'd like black pyjamas too but I can't find any. I have to make do with navy blue.

Ace is much more difficult to please. The assistant tries hard with him, offering him army khaki or bright scarlet, but he's not interested in ordinary clothes. He wants a Tigerman costume and we can't find one anywhere. He starts crying and he won't stop.

'For God's sake, Ace, what's the matter with you?' Dad shouts.

He picks out a T-shirt, shorts and pyjamas for Ace, not bothering to let him choose. Ace is in despair. I pick him up and he sobs into my neck. I have a sudden idea.

'Dad, can we go to the toy department?'

'The toy department? You kids, you're always after something. Aren't you getting a bit old for toys, Sunset?'

'It's not for me, Dad. I've thought of something we could get Ace. I promise it's only little, not at all expensive.'

'Ace doesn't deserve anything he's acting like a spoiled brat,' says Dad, but he gives in.

Lizzi huffs and sighs when he says we're going to the toy department, but she acts like she loves it when we get there. She and Dad muck around with the teddies, making them bob about and talk to each other. It is seriously embarrassing, but I ignore them and search hard, holding Sweetie's hand and lumbering Ace along on my hip. Then I find what I'm looking for: face paints!

'Here you are, Ace, this will do the trick!' I say.

He stops grizzling to peer at the tin. 'That's make-up!' he says. 'That's not for boys.'

'No, no, it's magic sticks of paint for your face. I'm going to paint you. I'm going to use the orange stick and the black stick, with maybe the pink stick for the nose and guess who you'll be?'

Ace shuffles uncertainly. 'I don't know.'

'Of course you know. You'll be Tigerman!' I look at Sweetie. 'And I'll paint you too, with blue shadow for your eyes and red lipstick, and you'll be a fairy-tale princess.'

I take them back to Dad, both smiling. I want him to say, 'Thank you so much for calming them down, Sunset. You're so good with your brother and sister. What would I do without you?' But surprise surprise, he just smiles back at us and buys the face paints, saying mildly, 'What do you want them for?'

So I start to tell him, and he nods a bit, but I know he's not really listening, and then he's distracted anyway because two silly grannies start squealing and blushing like schoolgirls, begging him for his autograph. Big Mouth laughs at them, raising her eyebrows at us. She's more interested in the face paints.

'Oh, cool! I love face paints! I used to run the face-paint stall at my school fete. I love doing it. Wait till we get back to the hotel, you three, and I'll make you all up.'

'They're my face paints. I want to do it,' I say childishly.

She shrugs. 'OK. No probs. You do it, Sunset.'

So when we get to Dad's hotel suite (which is huge, like an apartment, with so many flowers and ornaments and fancy bits I'm terrified Ace will knock them all over), I have a go at painting Ace's face like a tiger. It's much more difficult than I thought. I can't get the stripes to go right and he doesn't look fierce enough.

'You're Tigerman now, Ace. Oh goodness, I'm scared of you!' I say nevertheless, but he scowls at himself in the mirror, not convinced.

I try with Sweetie too, but the colours are too strong and she doesn't look like a fairy princess at all. She looks like a pantomime dame. Her chin quivers when she sees herself.

'Maybe it was a silly idea,' I mutter. 'I'll wash it all off.'

'Have a wash in my big bath,' says Dad.

It's an enormous bath made of blue marble. The water comes out of the silver dolphin taps already blue too! There are all sorts of soaps and shampoos and bubblebaths. I wish I could lie back in the bath all by myself and pretend to be a movie star, but I'm stuck with Sweetie and Ace. I don't even take all my clothes off to get in the bath because I'm worried Dad or Big Mouth will come in. Sweetie and Ace strip off and splash around and pretend to swim and cheer up considerably. I'm anxious when a lot of the face paint is wiped off on the snowy white towels, but Big Mouth Liz shrugs again when she sees.

'We'll get housekeeping to bring us more,' she says.

She's eyeing up her face in the mirror, putting on more lipstick. I bet she gets that all over the towels too.

'Could you do my face so it looks properly like a princess?' Sweetie asks her.

I'm taken aback by her betrayal. Liz paints her a beautiful princess face, with little blue and lilac flowers on her cheeks, silver stars round her eyes, and a tiny blue butterfly shimmering on her forehead. Sweetie is delighted, running around in just a towel to show Dad. He bows to her and acts as if he's blinded by her beauty. Then it's Ace's turn. Big Mouth turns him into a magnificent Tigerman. She can do all the stripes the right way. She can even manage whiskers, and she makes him look comically fierce. I remember how she held Ace in her arms at the premiere of Milky Star. It's only a few weeks ago but it seems like years now, so much has happened since.

It's all Big Mouth's fault that our family's been ripped apart and made so unhappy. I think about Mum at home and how miserable she'll be. She'll drink much too much and I won't be there to help her up to bed.

I glare at Lizzi when she asks me if I'd like my face painted too. 'No, thank you,' I say coldly though I'd actually love to see what I look like with flowers and stars and butterflies on my face.

'OK, I'll make your dad up then,' she says.

I think Dad will make a fuss but he sits obediently on the bathroom stool and lets her paint his face. He's actually chuckling, enjoying himself. She turns him into a vampire, making his face very white, with dark rings round his eyes and blood trickling from the corner of his mouth. He looks pretty scary, and Sweetie and Ace squeal in delighted horror. Dad chases them round the suite pretending he's going to bite them, and they charge about, shrieking.

'Dad, Dad, you're getting them too excited,' I say. 'They won't settle at bedtime.'

Big Mouth looks at me. 'How old are you, Sunset, seventy? Why can't you lighten up and let everyone have a bit of fun?'

She's not the one who gets woken up in the middle of the night with Ace screaming that the vampire's going to get him and bite him to bits. I have to rush Sweetie to the toilet too because she feels sick. Dad ordered room service for our dinner and let us choose anything we wanted. Sweetie chose three puddings Ice-cream Delight, Chocolate Heaven and Lemon Yum-yum. They're not at all delightful or heavenly or yummy when they splash into the toilet. Sweetie needs a lot of mopping up and cuddling afterwards.

None of us sleep properly after that. We huddle up together in this king-size bed in the second bedroom. The pillows are too fat and the sheets are too tight and the room is too hot. We turn and fidget and fuss in our unfamiliar new nightclothes. Eventually I lie on my back and put my arms round both of them and they go to sleep at last. I stay wide awake, getting pins and needles in both arms. I try to pass the time by writing a song in my head, but I'm too tired and uncomfortable and feeling pretty sick myself. I ordered a salad thing from room service because I wanted to seem sophisticated. It came with black olives and terribly smelly fishy things that looked like worms. When I eventually fall asleep I dream about them wriggling inside my tummy.

We wake up late, but Dad and Big Mouth are not up yet, sleeping on and on and on, their bedroom door firmly closed. I take Sweetie and Ace to the bathroom and we all get washed and put on our new clothes. We forgot to buy any underwear or socks, so we have to make do with yesterday's.

We go into the great big living room and I work out how to switch on the huge television so we're OK for a while, but we're all getting very hungry now, especially Sweetie, who lost all her puddings. I don't quite dare order room service, but I find a big fridge full of drinks and snacks, so we have a very odd breakfast of Coke and peanuts and Pringles and chocolate. Sweetie feels a bit sick again afterwards, and the Coke makes Ace burp a lot. He keeps on doing it just to be annoying.

'I'm bored,' he says. 'I'm going to wake Daddy.'

'No. You can't. You know you can't wake him in the mornings. Besides, she'll be there.'

'I don't like her,' says Sweetie.

'You did yesterday when she painted your face.'

'No I didn't! I was just pretending because I wanted to look pretty. I don't really like her one bit,' she says.

'I don't like her either,' says Ace. 'Mum's much nicer. Why does Dad like her better than Mum?'

'Oh, you're too little to understand these things,' I say, though I don't really understand why either.

When Dad and Big Mouth get up at long, long, long last, we have a room service breakfast with them, though it's more or less lunch time now. Dad says he wants to take us all out. Ace asks to go to the zoo to see the tigers, even though he's been to the zoo and seen for himself that there aren't any tigers there.

'I know another zoo a good zoo, specially for children,' says Big Mouth. 'There aren't any tigers there are mostly little furry animals like monkeys but you can get right up close to the meerkats. You know what meerkats are, Ace?' She does a sudden amazing meerkat impression, sticking her neck right up and quivering her nose, looking so comically like a meerkat that we all burst out laughing.

So we decide to go to this zoo in Battersea Park. Dad keeps on ruffling Big Mouth's hair, pretending to feed her titbits and calling her 'my little meerkat' which is totally sickening. But she's right, the zoo is lovely, and we can wriggle down a tunnel and put our heads up right inside the meerkat enclosure. Their little beady eyes stare back at us as if we're the funny animals.

Ace likes the pot-bellied pigs too, though I have to hang onto him hard to stop him hurtling over the fence to get in with them. Sweetie likes the yellow squirrel monkeys. I prefer the little mice, who have their own big mouse house with proper furniture. I wonder about Wardrobe City and think how incredible it would be if I had real mice running round all its rooms, standing at the stove, jumping on the sofa, curling up on the bed. I wonder if I could secretly get just two little mice, though maybe not a boy and a girl because then they'd mate and there'd be lots of babies.

I look at Dad and Big Mouth. He's walking with his arm round her, cuddling her close. What if they have a baby? When Big Mouth stops and bends over the fence to stroke a big white rabbit (showing a great deal of her legs), I tug Dad's hand, pulling him a few paces away.

'Dad Dad, can I ask you something?'

'What's that, darling?' says Dad. He's acting very relaxed and smiley lots of people are recognizing him and he grins and nods all the time.

'Dad, do you love Lizzi?'

He looks at me in sudden surprise. 'Did your mum tell you to ask me that?'

'No!'

Dad laughs. 'Well, it's her favourite question too.' He waves in a courtly fashion to a bald grand-dad who gives him an eager thumbs-up sign and plays an air-guitar in homage.

'So do you?'

Dad sighs a little. 'I don't know. Give me a break, Sunset.'

'But I need to know, Dad. Are you really in love with her and planning to stay with her for ever or are you going to come back to us?'

'I tell you, I don't know. I just want to have a bit of fun, for God's sake. Is that too much to ask? Your mum's doing my head in, Sunset. She does her nut if I so much as twitch when a pretty woman walks by. I can't stay cooped up at home for ever. I'm used to walking on the wild side, being on the road, a different gig every night . . .'

I stare at Dad. He hasn't done a tour for donkey's years. He hasn't had a new album to promote. So what is he going on about? He's playing pretend games with Lizzi, kidding himself he's young again. It's like he's stepped into his own Wardrobe City.