THE youngster in the soldier's uniform running scared across the muddy First World War battlefield looks barely old enough to shave, let alone take up arms for his country. And, just as Private Charlie Shakespeare wants to prove his worth, so the actor playing him on screen in the new film Deathwatch is fighting to show he wasn't a one-hit wonder.

Two years ago Jamie Bell was the toast of not only the British film industry but Hollywood as well. His mixture of raw talent and gritty defiance as Billy Elliot, the miner's son who wants to be a ballet dancer, helped make the movie one of the biggest British screen hits of recent years.

The 13-year-old schoolboy from Billingham found himself feted and acclaimed around the world. He mixed with Hollywood royalty like Julia Roberts, and became chummy with Russell Crowe. He even beat the Gladiator star to win a Bafta best actor award. And then he went back to school.

Now 16, Jamie's waiting nervously for the release of two new pictures - the First World War horror story Deathwatch and a fresh screen adaptation of Dickens' Nicholas Nickleby, in which he plays the crippled Smike. He seems confident enough, even admits he's "the same cocky little guy" he was before Billy Elliot kickstarted his acting career. But talking to him, it's apparent that he knows his future rests on reaction, both from critics and the public, to these two films.

"The most important thing is to have people who can advise me on what to do. Having them is a lifeline to make sure you don't go down the wrong road," he says.

Equally important is maintaining links with the North-East. He still lives with his mum Eileen in Billingham, where his Bafta award resides not in some place of honour but on the floor. She'll travel with him to New York this month to publicise Nicholas Nickleby, which is being released in the US to qualify for the Oscar nominations.

'I don't think my life has changed," he says. "I still have the same friends. If anything, it's united my friends more. I've been home a lot recently because I have a lot of commitments up there. My mum, my sister, girlfriend and stuff. It's difficult maintaining a relationship when you're jetting around the world. But if you combine a trust between you, and she knows how I feel."

There's been no big spending spree as all the money he's earned is "locked away", although he only has to ask if he wants to buy something. "I've been a good boy, I really have. It's important I have people there saying, 'don't touch that yet, you don't need it'," he says sensibly.

Jamie, and those around him, must be well aware that show business is littered with the corpses of youngsters who found fleeting fame, only to crash and burn, then return to obscurity. Their brief encounter with celebrity disappears all too quickly, lives ruined by an excess of drink, drugs and sex.

Tonight's BBC2 programme Fame, Set And Match illustrates only too well the fluctuating fortunes of those who start acting from an early age. For every Jodie Foster, there's a Corey Feldman. Both began appearing in commercials when they were barely out of nappies. One became an Oscar-winning star and director, the other blew his chance of stardom through unwise film choices and a wild lifestyle.

Some youngsters fail to make the transition for another very good reason - lack of talent. Jamie clearly has that, as his performance in Deathwatch demonstrates. Now it's a case of channelling it in the right direction. He took his GCSEs this year - gaining two As in English; Cs in geography, French and history; Es in maths and science - and has decided not to go on to college, although drama school is an option he's considering.

The offers that came his way in the wake of Billy Elliot were politely rejected, mainly because they were "child roles". He preferred to join the promotional tour and awards ceremonies for the movie, not just to enjoy himself but to school himself in how the business worked.

'It was a big task because Billy Elliot did rest on my shoulders a lot and became a household name for a while. People expected me to do press and everything. I was happy and saw some great places. I went all over America, which was brilliant," he says.

"Returning to school was hard because that meant it was the end of Billy Elliot. It was a case of now let's get back to life. I just went back to school. Then it came to summer and I thought I'd start looking for some work.

"Now I know this is what I want to do. Acting is an unstable job. You're employed one minute and not the next. You can't trust it. I was making a lot of choices for myself, and had people advising me. They didn't want to see me go down the wrong track.

"It could so easily happen. It's appealing for anyone to just grab it with two hands and say, 'I want it now'. But you don't need to take it. If you're clever enough, you can keep going and work. And it's the work that has to be rewarding."

One film, set during the Second World War, was lined up, only for the finance to fall through twice. The project now looks likely to shoot next year. Deathwatch seems a strange choice on the surface but fitted his criteria. He's part of an ensemble company of youngish British actors, rather than being the above-the-title star. He didn't want it sold as a Jamie Bell film.

"I needed to find something to help me from child actor to adult actor. It's very difficult to do. We've seen different examples of where it's not worked out," he says. "The last time people saw me I was a happy, dancing kid with ballet shoes round my neck. I don't think there's a better way of doing it than being seen dodging bullets. The first thing they're going to say is, 'he's grown up'. I need to lose Billy Elliot really, which is difficult when you've created a label for yourself."

Now, Bell is waiting for the right script to come along again while trying to lead as normal a life as any other growing lad of 16. "People will push out advice if they think you're going to listen. I take it and understand it. There's a certain point where you have to say, 'I'm going to take control' and people have to stop controlling me," he says.

You get the feeling that the likelihood is that level-headed Jamie will be more of a Jodie Foster than a Corey Feldman when it comes to making the transition to adult actor.

* Deathwatch (15) opens in cinemas on Friday. Fame, Set And Match is on BBC2 tonight. Billy Elliot is showing on BBC1 over the Christmas period.