Why I'll never let my son watch me in Rome

On the day I meet him in a photographic studio in Islington, he is doing a cover shoot for a gay magazine. But, as if to underline his metrosexual appeal, the shoot he is doing the next day is for Vogue.

He is, of course, smart enough to know that he won't get far complaining about being too handsome, but the thought lingers behind much of what he says. "I'm not saying I'm good-looking, but I think I know now, having played this run of parts, that I probably do fit into a stereotype of what people perceive to be good-looking. And it's not particularly useful."

People would often say of Purefoy that he was almost too good looking to be a true star in the past. He had a sort of baby-faced beauty. Ageing, albeit gently, along with playing such a gutsy part, has been a blessing in terms of broadening his appeal.

Purefoy was brought up in Somerset by middle-class parents who split up when he was four. His mother, a businesswoman, ran an employment agency in Yeovil, while his dad, a farmer, became an agent for a local Tory MP (Purefoy supports Labour). His route into acting was unconventional. He was a boarder at Sherborne in Dorset, which he didn't enjoy, though he no longer wants to labour the point.

At school, he says, there was an expectation of the life he was being prepared for. Pupils were expected to go into industry, the military or law. Being good at sport helped. "There was a great deal of regimentation in terms of uniform: you would get good jackets and waistcoats if you were good at things they thought you should be good at. You didn't get a good jacket for playing Hamlet."

He left school at 16, and worked as a hospital orderly for two years. "That woke me up a bit. Hospitals are extreme places. You can be in a maternity ward seeing a child being born and 20 minutes later watch somebody die. I worked in the mortuary for a bit. I was 17, you know. I used to put people in fridges."

He was planning to take exams to allow him to become an operating theatre assistant, when his father intervened, urging him to go to college and sit his A-levels. One of them was drama.

"The acting profession is full of misfits," he says. "It's full of people who aren't happy in their own skin. And for a short amount of time you get to be somebody else, and behave in ways that maybe you'd like to behave, but can't, as yourself. It's about escaping, probably."

Rome was a big commitment, which dominated his life for the two years of filming. Twenty days a month were spent on location, and Purefoy "bust a gut" to get home to London whenever he could to see his son. "He gets a bit sick of me after 10 days anyway," he says, though he is clearly pained by the necessity of these frequent separations.

His girlfriend Jessica Adams is an art historian who worked on the series, and has been working with their mutual friend, director John Maybury, on other projects. "She's super-smart, and very strong-minded."

Purefoy refers to himself as "a serial monogamist", although his reputation is something of a heartbreaker. He has had two high-profile relationships. The mother of his son is Holly Aird, star of the television series Waking the Dead. "What happened? You grow apart sometimes. The trick is to see it not as a failure, but as part of your life. And we're still really good friends. I love her dearly. She lives close to me, and we look after Jojo as a team. We talk nearly every day. I'm blessed, really, because you read about some people who split up. We never had lawyers.

"The only thing lawyers want is to string it out because that's more money for them. Sit down and talk to a relationship counsellor about how to break up. Holly and I never argued about Jojo or property, neither of us was unfaithful, and that took an awful lot of the poison out of it."

His other big relationship was with Cold Feet star Fay Ripley. They were together for 11 years. "That was a long one. I think we were too young. We were Romeo and Juliet together. That's how we started."

He gets a little misty-eyed about the notion of first love. "There's no cynicism. There's no sense of 'Oh, I've seen this one before, here it comes.' You're fresh, you take everything as it comes. It can also be the most hurtful, because when things start going wrong, you've never felt anything like that before. We were just young, and we probably went out with each other for a bit too long."

When Purefoy's son talks to him about acting, he often asks whether his dad is playing a goodie or a baddie. "I'm always telling him it's never quite as simple as that. There are baddies and goodies in Star Wars, but I don't really do Star Wars. In some things there are bad people who've got good hearts, or good people who've got bad hearts, and it's just a little bit more ambivalent and ambiguous. Life isn't always black and white."

Mark Antony, he concedes, is mostly bad. "He's flawed but he's human. I think the audience can tell that there's hot blood running through those veins."

And Purefoy? Well, he's certainly charming company, engagingly self-deprecating, and apparently hot-blooded. But for all his matinée-idol looks, he seems most interested in flaws.

Towards the end of our conversation he suddenly gets very animated about Botox, and a story he read in the paper, in which a taxman rejected an actress's claim for the treatment. "He turned it down on the grounds that as an actor you need flexible face muscles to be able to do your job. The more Botox you have, the less your face can move. The less you can show what's going on inside the character, the less characters you're going to play. If your career is based on you looking young, you're fucked, aren't you, when you're 50?

"Look at me," he exclaims suddenly, pulling at his features. "It's like a field in Suffolk, my forehead! In winter. You could plant barley in these lines. And I'm 42. This will get worse. Good!"

Unlike Mark Antony, who doesn't last the series, Purefoy is hoping to be around for some time.

Rome is on BBC2 on Wednesdays and Sundays at 9pm.