Ashley Walters's second act

When I meet Ashley Walters he's preparing himself for his latest role at the Royal Court, which involves full nudity. 'I've never done it before. There's nowhere to hide on stage, is there?' Thank goodness he is, to use the technical term, totally buff. He works out religiously. 'For me, exercise isn't really about being healthy, it's more about vanity. I'd prefer to look good when I take off my top.'

The charmingly candid Mr Walters has done a lot of living in his 27 years, with three children, two careers and one stint in jail behind him. Born in Peckham, he went straight from doing his GCSEs to joining So Solid Crew, that merry band of South London rappers who had, in the words of their number one hit single, '21 seconds to go!' Alas, barely that long, as it turned out: after a spate of violent incidents at their gigs, the Crew went silent in 2001. With five of their number in custody, there was no one left to do any singing.

Ashley paid the price for being caught in possession of a firearm (a stint behind bars) and managed to emerge stronger, wiser and ready to bare everything at the Royal Court. 'I had to distance myself from that whole world otherwise I wouldn't be speaking to you now. I've only just started talking to Mega [So Solid co-star Megaman] and some of the others again.' If you look hard enough, you can see the scars: physical - there's a dark splatter on his neck where he was attacked with a broken bottle - and emotional. He walks into Oriel café on Sloane Square carrying himself like a young prince, walking tall and radiating confidence, but halfway through our interview he says: 'I don't come round these parts of town very often. It's intimidating, isn't it? Or maybe I'm intimidating to people here.'

This from a man who has had huge commercial success in music and acting, releasing five albums and counting (there's a hip-hop collaboration with The Wire's Idris Elba in the works) and winning Best Newcomer at the British Independent Film Awards for his performance in Saul Dibb's Bullet Boy. He recently pulled off a 1940s Jamaican accent for the BBC's costume drama Small Island in which he played the charmer Michael Roberts. Ashley's maternal grandmother, who came over from Guyana in the 1950s, helped him get a sense of period. 'That was a challenge and I love that.' Too often he finds himself typecast as an inner-city ex-con. 'A lot of people just want me playing myself, keeping me in my box. Some days it seems I've done as much as I can here and I think I'll go and try my luck in America. But then a call comes from the Globe theatre. They want me for King Lear, playing Edmund. You know, the bastard?' His face, which is very still, doesn't betray much emotion but you can detect excitement in his voice. 'But I'm not ready for Shakespeare yet. It's like a foreign language. One day.'

For the moment, then, he's playing an excon, David, in Off The Endz by 28-year-old Bola Agbaje, a British playwright of Nigerian origin, which previews from Thursday at the Royal Court. The script is full of street slang, which Ashley patiently translates for me. A zoot is 'a joint', a neek is 'a boffi n' and to merk someone is, 'Well, there's no nice way to put it, it's to kill someone.' Ashley's character is furiously unwilling to pay taxes, and makes his money dealing drugs. 'Growing up I met a lot of people with the same views and opinions as him,' he says. 'And at some points in my life I've probably thought about going down that route myself.' Dealing drugs? 'Yeah. I grew up next door to a very big drug dealer. I don't want to bad-mouth him, because he got out in time, he wasn't greedy, and he always encouraged me with my acting, and to do something better than him. But it's hard to tell a young kid, "Do something legitimate," when you're a drug dealer driving around in a Mercedes and wearing a lot of jewellery. All that was very attractive to me. It was just because I was fortunate enough to have some different influences that I was deterred from doing it myself.'

That lifeline came in the form of the Sylvia Young Theatre School, where Ashley's mother Pamela, a council worker, started taking him on Saturdays when he was seven. 'She had me when she was 18, so by the time I was seven she was still only 25, really young, and single as well, so having me there gave her the chance to do whatever with her mates.' Ashley was soon centre stage. 'I loved the buzz, I just wanted to get up there.' He's a natural performer, magnetic and thoughtful, and it was all the training he seemed to need. He says he learned a lot from working with actors such as Adrian Lester (on the BBC drama Hustle) and Tom Hardy (on the horror film Waz), who have both become friends, 'although I find it hard to say I'm mates with them because I look up to them so much'.

The technique he developed in early stints on The Bill and Grange Hill was to try to keep his performance 'as real and true as possible. I try not to read my lines too much, to keep it fresh, and to play it through my face rather than my body. But I'll be honest with you: I'm winging it. I've been working it out as I go along.'

Aged 13 he got into Pimlico School, which was known for its drama department. Money was tight: his father had six sons, by six different mothers. 'He was in and out of prison throughout my life. I didn't know him at all well. I had a lot of difficulties finding myself and focusing on my work and I realised that if I was going to understand myself I had to understand him first. That was my mum's good advice. So when he was dying of lung cancer, I took him in and cared for him.' A pretty brave move. 'That's me, going in at the deep end, as usual. I spent every day filming him and I watch the tapes to this day. It's very therapeutic. A lot of the things that I thought happened because I wasn't good enough were actually because of him. He'd been neglected while he was growing up and he'd been in and out of borstal and foster homes, and I realised that I've got to break this cycle with my own kids. It made me adamant I had to be there for them.' Ashley and his school sweetheart Natalie Williams have a daughter China, who's eight, and two boys of ten and six, Shayon and Paniro (the latter name being a conflation of Pacino and De Niro, two of Ashley's favourite actors). It wasn't his plan to have children so young. 'I'd never call my kids an accident, but it did come from nowhere for me. At first I was very selfish about following my career. Then I took my eldest along with me on tour and we developed an amazing bond; it's really hard to be separated, really hard.'

That happened when Ashley went to prison in 2002. An innocent shopping trip in the West End went wrong after he shouted at a traffic warden, who then called the police. Searching his car, they found a loaded Brocock air pistol hidden in a sock in his girlfriend's handbag. It had been modified to fire live ammunition, and had been acquired by Ashley in a nightclub in Harlesden at the inflated price of £1,300 (it was actually worth about £300). What was he thinking? 'I'd had a lot of bad experiences: I'd been stabbed, and threatened; I'd had someone put a gun to my head when I had my six-month-old son in my arms. Like a lot of people in Peckham and So Solid, I had a bad relationship with the police and so, instead of going to them, I thought I needed a gun for my own protection.'

These arguments were rehearsed before a judge, who was more impressed by the charity work Ashley had been doing in private. 'At that time I was paranoid, too. Paranoia is a disease. I'd got myself into a state where I couldn't walk from my house to my car without experiencing some sort of confrontation. I was smoking a lot of weed at the time. Not a good idea for anyone in that position.'