'I thought you could have it all'

She slurps Coca-Cola loudly through a straw and glares at me. One of her make- up/ hair/ clothes/ whatever stylists comes to say goodbye to Ruby. "I shall expect lots of wit," she says. I can't help thinking to myself, that might be a lot to expect.

But this is the thing about Wax. On camera, she's loud, charming, fun. Off it, she's cold and difficult. I can't work out why she's like this, why it seems to be too much effort to flick that showbiz switch for half an hour, and answer with more than a "Yuh" or a snappy "What do you think?" Either she can't be bothered, or she just doesn't care what people think about her.

Or maybe underneath all the brashness, she's cripplingly shy and insecure. But it makes it impossible to like her.

She was very open when she wrote and publicised her autobiography, How Do You Want Me? She grew up in Evanston, Illinois, the only child of Edward and Bertha Wachs. Her father, an Austrian Jew who escaped before the Second World War, manufactured casings for hot dogs and became wealthy; her mother was a beauty who spoke nine languages and had Ruby in her late forties.

Wax had a bizarre childhood, which would later make it into her stage show and book. Her mother kept the curtains of their house closed to protect the furniture and kept the plastic wrapping on the sofas. Her parents fought constantly and her father often beat her with a hairbrush or a belt. She suffered from dyslexia as a child and was often told she was stupid.

Why does she think she never had her confidence knocked out of her? "I couldn't tell you that. You'd have to ask my friends ... I don't know." Ask her anything touching on the personal and she looks uncomfortable and starts talking pointedly about her work, trying hard to justify her new role.

"If you're going to work in TV," she insists, "this [the Bafta red carpet show] is the job to take because (a) you don't have to deal with the B-list, (b) you can talk about anything and (d), you're wearing really expensive diamonds." I'm left wondering about "c". Maybe it's (c), the BBC haven't recommissioned any of Wax's shows.

She points to the man in the suit sitting behind me. "He's guarding them [a diamond necklace he tells me is worth £1.4 million which he carries around in a leather pouch inside a very scruffy Dunlop rucksack] because I had them on. I'm tempted to run with them but I think he'd catch me." Does she own things like that? "No, it's exciting. I don't spend money on jewellery and neither does my husband. He bought me this [she flashes her gold wedding ring]. He bought me a Chuck Norris Total Gym for Christmas. It's still in the box. He's so romantic."

I ask her what she does like to spend her money on. "Holidays. I love hotels, more than anything else, probably, in the world." She is off on a roll. "I am going to live in a hotel. I don't care which one, it could be a Holiday Inn, that's how much I love hotels. My husband could visit. He could have his own room ... I'm having trouble breathing. I need to get this corset off." She goes into the other room to change, then she's back, wearing a green top underneath a black fitted Armani jacket.

Wax has been married to the television producer Ed Bye since 1988 (they met when Wax was writing and starring in Girls on Top with Dawn French and Jennifer Saunders) and they live in a big house in Notting Hill. They have three children, Max, 17, Madeleine, 14, and Marina, 12. On the surface it looks as if she has had it all.

"I don't know if it's all successful," she says. "It's a big mistake to try and have everything. I don't think it works at all ... I thought you could have it all but you can't, it's impossible. When it's going on, it's too much. But the good news is your kids grow up. If they're on heroin, chances are you made some mistakes. If they're well adjusted, you got away with it. There's nothing else to test it. My kids are OK but it was detrimental to my health to be that ambitious, to go to Russia to film when I was in my ninth month of pregnancy, it wasn't safe. I got away with it but somebody else could have had a miscarriage. I wouldn't encourage it in the next person."

After the birth of her last child, Wax suffered post-natal depression and checked into the Priory. "You don't calm down, you just make sure you're doing what makes you happy. That takes a lot of time. You think, 'I need to keep doing the same thing harder, faster and longer.' But it took me a while to go, 'Wait a minute, do different things.' This [the E! Bafta show] is more fun than doing a daily show, which I found nauseating. I'm back with really interesting people instead of pretending to be interested in people I wasn't interested in. I hated it."

She says what really makes her happy is travelling. "But not in a private villa. I like to get out in the lobby and mingle. At this moment I'd say I'm happy, in 10 years it could change again. By then I'll be Joan Rivers's age and I'll still be on the red carpet in sequin incontinence pants. I'll be asking people their names over and over again. 'I know who you are, wait, give me a clue'."

She recently bought a flat in an exclusive enclave by the Thames in Battersea. She also has a country retreat in the Cotswolds which she rents out. Last year it was reported that Wax had objected to the building of a disabled ramp that the Couper Collection, a floating gallery, wanted to build. "Oh no, that's not true," she says. "That's so off the wall. Why would I object to a disabled ramp? It wasn't even about that."

Our photographer arrives and Ruby goes into her dressing room to be poured back into her corset. Is she vain? "I am right now," she says as the photographer points the camera at her. What about when she's at home? "No, I wear jogging pants." Does she like the way she looks? "It's too late for that. I would have liked to be taller and thinner but what can I do?" She does look good. She pouts and smiles and camps it up for the photographer. Finally, the Ruby Wax I recognise.