Click here to watch a clip of Son of Rambow

If Noël Coward’s Mrs Worthington were alive now, it’s not the stage she would be pushing her daughter towards, but the film set. The opportunities available to today’s young performers, not to mention the high calibre of those who make it to the screen, can be gauged by glancing at the nominees for this year’s best-picture Oscar. Atonement, Michael Clayton and There Will Be Blood all contained excellent work by children, while Juno depended for its success on a largely teenage cast. Saoirse Ronan, from Atonement, was even nominated as best supporting actress, up against Cate Blanchett and the eventual winner, Tilda Swinton.

Any whippersnappers with cinematic ambitions may eventually encounter Susie Figgis, the eminent casting director who has discovered some of the most striking child actors in modern cinema: Jodhi May in A World Apart, Eamonn Owens in The Butcher Boy and Daniel Radcliffe for Harry Potter were down to her.

Now she has struck gold again, twice, in finding a pair of daredevil tykes to star in the new British comedy Son of Rambow. The film follows two 11-year-old boys, the introverted Will (Bill Milner) and his rough-and-ready chum Lee (Will Poulter), as they shoot an insanely ambitious amateur sequel to the Sylvester Stallone vehicle First Blood. “I saw those boys together and thought, unless something gets badly screwed up along the way, this will be great,” Figgis recalls when I drop in at her north London office.

Garth Jennings, the film’s writer-director, agrees. “They were fantastic, so natural. They’d never acted before – or one had been a Munchkin in a school play. They wandered in, completely unaffected, with no previous intention of doing this sort of thing.” Figgis thinks this is one of the keys to good child acting. “I practically always choose kids who’ve never done acting training,” she says, “because I think their training gets in the way of being real. I hardly ever cast from drama school. The only exceptions I can think of are Freddie Highmore, for Charlie and the Chocolate Factory, because he had something extraordinary, and AnnaSophia Robb, who played Violet Beauregarde in the same film. She’d done lots before, and that really suited the part. I was taking her to meet Tim Burton in a hotel in Los Angeles. I thought it must be rather scary for her, so I said, ‘Do you enjoy doing this?’ And she said, ‘Oh yeah, I love it, I’m a people person.’ Only someone from that world would have come out with that, but it was completely sincere.”

The qualities Figgis looks for in a child performer are, she says, markedly different from those that make an adult actor stand out. “When you’re casting a child, you have to find the thing that works for that film and run with it, which is why kids who are good in one particular part often don’t go on to be adult actors.” There is a moral responsibility that comes with propelling a child, however willing, into the limelight. Many dazzling child performers have matured into fine adult actors, from Mickey Rooney to Jodie Foster and, more recently, Jamie Bell. Yet for every youngster who handles youthful success, and even builds on it, there are hundreds more who fall by the wayside. Some, such as Drew Barrymore, are lucky to be alive, let alone have healthy careers. Others, such as Macaulay Culkin, have had to negotiate a domestic minefield that no amount of fame or wealth could make worthwhile.

Then there are the worst-case scenarios – River Phoenix, say, or Brad Renfro, the child star who held his own against Susan Sarandon and Tommy Lee Jones in The Client, and Ian McKellen in Apt Pupil, but was found dead earlier this year, aged just 25.

“The child’s emotional welfare is at the forefront of my mind,” Figgis says. “I meet a kid a minimum of three times before casting. I like to meet the parents and encourage them not to get overexcited about the glamour of the film world. I try to set up the money so it goes into a proper savings account. You have to be extremely careful about everything – it’s on your back what happens to these kids. You can mess up their lives if you’re not careful.”

Things look rosy, however, for the stars of Son of Rambow. “Bill and Will had a ripple effect on the whole production,” Jennings recalls, smiling. “When they’re laughing and becoming friends in the film, we were just shooting what was really happening.

“They instantly became best pals, and their families have been on holiday together since. It makes it a hell of a lot easier than trying to coax naturalistic performances out of terribly serious young actors who desperately want to make it in movies.”

Son of Rambow is out on Friday

Consider yourself one of the family

Shareeka Epps in Half Nelson (2006) Ryan Gosling may have got the Oscar nomination, as a teacher whose heroin habit intrudes on his work, but it was 17-year-old Epps who held this impressive film together as the pupil who happens on Sir’s nasty little secret and becomes his cool, calm confidante - as well as his biggest chance of redemption.

Abigail Breslin in Little Miss Sunshine (2006) The 10-year-old was the heart of the ensemble in this modest indie comedy that hit big at the box office. Whether sweetly quizzing her suicidal gay uncle on his love life, hanging out with her drug-dependent grandpa or writhing inappropriately at the barnstorming beauty-contest finale, she was faultless and true.

Thomas Turgoose in This Is England (2006) As the tough-cookie skinhead with the soft centre, the 14-year-old was captivating. Shane Meadows’s state-of-the-nation pic wasn’t always subtle, but little Turgoose, in red braces and DMs, kept you focused on the human cost of indoctrination.

Dillon Freasier in There Will Be Blood (2007) Look at that angelic but withdrawn face, the pale complexion. Long before he loses his hearing in an explosion and is abandoned by his father, the newcomer (who got the part after his traffic-cop mother pulled over the film’s casting director for speeding) has the audience wrapped around his pinkie.

Georgia Groome in London to Brighton (2006) Jodhi May lookalike Groome was 13 when she played the runaway pressganged into prostitution. She stars in Gurinder Chadha’s forthcoming Angus, Thongs and Full-Frontal Snogging, and has just finished shooting Brit horror flick The Disappeared.

Devon Gearhart in Funny Games (2007) The 12-year-old is a US film and television veteran, but there’s nothing affected about his performance as part of a family terrorised in their holiday home. You can only hope a therapist was on hand.

Cameron Bright in Birth (2004) An outlandish conceit – 10-year-old boy turns up on widow’s doorstep claiming to be the reincarnation of her late husband – was carried off thanks to the dazzling Bright. Now 15, he is accumulating a hefty CV (Juno, X-Men: The Last Stand, Godsend).

Saoirse Ronan in Atonement (2007) As the meddling go-between who derails the lives of James McAvoy and Keira Knightley’s characters, she outshone them with a performance of eerie concentration. Soon to be seen in Peter Jackson’s long-awaited film of Alice Sebold’s The Lovely Bones.

Ed Sanders in Sweeney Todd (2007) Luckily, Tim Burton picked the 14-year-old, urchin-like Sanders, who had no musical training, over others with backgrounds in singing. Watch carefully and you’ll see his height change during filming. Growth spurts, eh? What can you do?

Austin Williams in Michael Clayton (2007) As the son of George Clooney’s legal “fixer”, the 11-year-old serves as a soothing ally to the delusional Tom Wilkinson and provides a focus for Clooney’s conscience. He was also good as the young Matt Damon in The Good Shepherd, wetting himself on Santa’s lap.

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