YOU HAVE to hand it to Anna Friel. Though she’s seven months pregnant and suffering from something truly vile, the 28-year-old has trooped to Kentish Town, North London, from her home in Windsor to be photographed in a Tommy’s T-shirt. Tommy’s is a charity that funds research into premature birth, stillbirth and miscarriage, and it is bringing out a black sleeveless T-shirt to raise money.

So Friel has come, small, verdant, fertile, in a blue Alberta Ferretti dress and flat round-toed gold sandals, to be photographed wearing it. When she shows me her teeth I can’t believe she left the house. “I’ve had such a good pregnancy, but I’ve got really bad sores on my gums. Can you see?” she asks, flaring her lips to reveal numerous bleeding, warty lumps nudging like moss between her teeth. I blanch in horror.

“Oh, these are nothing!” she cries in a rapid, flat northern voice. “I just underwent four hours of surgery to have the first lot cut out so the infection didn’t get to the baby. All these doctors kept saying: ‘It’s fine, they’re just these things called pregnancy tumours.’ But they were just getting bigger and bigger. I found a gum specialist and she said: ‘You must get them cut out.’

“But you’re not allowed anything when you’re pregnant, so she did 12 injections in the roof of my mouth. She said ‘Are you OK?’ and I said ‘No! I can feel you cutting my gums with a scalpel.’

“It was awful. David (Thewlis, her boyfriend of five years), bless him, was holding my feet. But the tumours have just started to come back. It’s incredibly embarrassing — you’re eating a meal in company and your mouth fills with blood.”

By now she has straightforwardly greeted all the people waiting for her — the T-shirt designer, the photographer, the girl from Tommy’s — and is sitting in the office beside the photographic studio, having tried to give me the only comfortable chair. “Do you have any biscuits or hot chocolate, because I’ve not had lunch?” she asks, and then starts talking, in the same calm, rapid tone, about absolutely everything in her life — her new film, her last film, her baby, how she got pregnant (“a happy mistake”), and David Thewlis.

He is a much respected actor, having starred in Naked, The Big Lebowski and now Kingdom of Heaven with Orlando Bloom; she has done 16 films that few people have seen. Yet she is by far the more famous, thanks to a stint in the 1990s as Beth Jordache in Brookside (she had the lesbian kiss), a notorious ditching by Darren Day (he ran off with Tracy Shaw, who played a hairdresser in Coronation Street) and a track record of going out with Robbie Williams and hanging out with Kate Moss.

I have to admit, I wasn’t excited about meeting her. Brookside babe, I thought glumly. Pretty girl about town, made lots of duff movies, not very interesting. But she is uplifting. Maybe it’s because she’s so happy, or maybe it’s her northern-ness, but I’ve not seen a celebrity so comfortable in their skin. There is no attempt to hide anything. She is warm and down-to-earth, with a nice streak of saltiness, like the rim on a glass of tequila. “I’m a bit stubborn. I don’t like being told what to do,” she says of the criticism of her friendship with Kate Moss and Robbie, “and I’m not going to not hang with people because it makes me look bad. They’ve got great, successful careers, and if they want to have that kind of lifestyle the only people they hurt are themselves.”

At 42, Thewlis is 14 years older than her. They met on a flight to Cannes. “It was the best of British: Kate Winslet, Jude Law, Sadie Frost, Rachel Weisz. All on the same plane. Can you imagine? ‘Britain’s film industry goes down!’ We were laughing about it on the plane. And we got on really well, I think because we were the only two northerners. He’s Blackpool and I’m Rochdale. But nothing happened.

“Then we met again two years later, but he had a girlfriend and had just split up with his ex-wife. It was two years after that we were taken to dinner by Bradley and Damon who own (the film production company) Natural Nylon. David had just finished his novel — just typed, literally, ‘The End’ — and they said: ‘We think you two would get on really well.’

“And we did. He came to my house that night and he never left!” Friel grins through shiny, swollen lips. “I’d stopped hanging out with Kate Moss by then and calmed down. I’d bought my place in Windsor. He came and said, ‘It’s really not what I expected’. I’m very grown-up with my house. I collect lots of antiques and Pre-Raphaelite paintings.”

I ask what she liked about him, and she says, promptly, his calmness. Then she says: “He had this thing when I first met him, that he kept rocking. I just thought he needed a great big hug!” The day we meet he has given an interview saying he used to be angsty, but she had made him a lot happier. Friel lights with pleasure when I tell her this. “That’s nice! Everyone keeps saying: ‘When are you going to get married?’ It’s like, ‘Give us a chance! Let’s have the baby first!’

“I think because he’s been married before and had all the romance and air go out of it . . .” she breaks off. “But I’ve never seen a man so happy at having a child. And we didn’t plan or try. Because my ovarian cyst burst four years ago and I had something called endometriosis, the doctors had said it would be very difficult for me to have children. And it literally happened after one time of being naughty!’