A quick curtain call. Then bed: Child actors in adult theatre

It's a blissfully sunny spring Saturday, a perfect afternoon for kids to kick a football in the park or play on the swings. Yet eight-year-old Lennie Harvey is locked indoors, in the warren of dressing rooms backstage at the Apollo theatre in London's West End. Lennie does have games to play, though: Ludo and table tennis. Of the latter, Lennie says: "I play it with some of the actors. There's someone called Tom. I've beat him twice, and I've beat my pretend Mum, and I've beat one of the men who beats up my Dad. And because I beat them all, someone gave me a chocolate bunny."

Mostly, Lennie is marking time, waiting for his call to join Mark Rylance on stage in Jez Butterworth's hit play Jerusalem. Lennie plays Marky, the neglected son of Rylance's character Johnny Byron, and a still point of innocence in the drug-fuelled turbulence of the story. He is tiny on stage, dwarfed by the trees that reach up to the theatre's roof – yet in his presence, Rylance's larger-than-life Byron is momentarily deflated.

Down the road at the Noel Coward theatre, 11-year-old Ellie Bruce and her father Bill are keeping themselves busy between her three brief appearances in Enron, as the daughter of company CEO Jeffrey Skilling, played by Sam West. Ellie has her own dressing room at the top of the building, with a mirror surrounded by lights, and a fridge containing juice and chocolate bars.

Ellie writes notes to the two girls with whom she shares her role, decorates polystyrene cups and plays on her Nintendo DS, bought with her earnings, while Bill reads the paper. But they prefer to pass the time downstairs, in West's dressing room, where the door is open to all. "We used to have activities down there," says Bill. "First there were black-and-white drawings to colour in, then puzzles. You'd think people who are well-known would be aloof, but Sam has time for everybody." Ellie agrees: "Everybody is really friendly."

When Ellie gets her call, Bill waits in the wings. Ellie hasn't got many lines; in her second scene, she mostly repeats the word "why", parodying Enron's slogan, "Ask why". But she's already learning to relish the live nature of theatre. "It's fun because I can vary the way I say things: I can be stubborn, or cute, depending on how I feel," she says. And, excitingly, West will vary his delivery in response. Ellie's only worry is audibility: the louder she speaks, the harder she finds it to maintain her American accent.

From Oliver! and Billy Elliot in the West End, to touring productions of The Sound of Music and Chitty Chitty Bang Bang, there are hordes of children performing on Britain's professional stages. But these are family shows, suitable for all ages. None of Lennie's friends from primary school have been to see him in Jerusalem, because admittance is restricted to the over-14s: the play's themes are too adult, its language too filthy. Lennie and Ellie do a particular, and quite peculiar, job: they are child actors who perform in a wholly adult environment, in shows their parents would never take them to see. It requires them to stay up well past bedtime – and, unlike their grownup co-stars, they also have to get up for school the next day.

Invariably, actors say they caught the theatre bug young: they were chosen for the school play, or they enrolled in drama classes when they realised they enjoyed making their friends laugh in the playground. Yet most wait until after school, or university, before performing for anyone other than their peers. Rylance and West started acting as children, but you didn't see them in a major theatre until they were over 16.

So who are these children taking on grownup jobs in British theatre? How did they get started? For some, it's merely a fluke. Late last year, 12-year-old Claude-Vivien Nkudibiza went along to a workshop at the Manchester Royal Exchange after a director sent a call out to local schools: as a result, he was cast as Travis in its production of A Raisin in the Sun. "It's really rare for a normal boy to get picked to be in a professional play," he says, describing the experience as "one of those once-in-a-lifetime opportunities". Yet this isn't the way most child actors think. They might attend regular schools, but most are also signed up with agents, whether from an independent company or attached to their drama school, and they go to several auditions a month – for films, TV, radio and adverts, as well as theatre.

It would be easy to assume that these are the beleaguered children of pushy parents, but Bill Bruce and Jackie Harvey, Lennie's mother, prove otherwise. "Lennie was quite reserved," says Jackie, "so we thought we'd try him in an after-school club, just to bring him out of his shell." His father had taken him to football, but Lennie wasn't interested, whereas dance and drama captured his imagination immediately. It's just coincidence that the nearest drama club to the family's home in London is the Sylvia Young theatre school, whose former students include Ashley Walters and Tamzin Outhwaite.

Ellie, meanwhile, started attending the Royal Berkshire Academy for Performing Arts every Saturday because her older sister went. This story is typical: Matilda Castrey followed her sister Madeline to an Italia Conti school near their home in Surrey, aged three. Five years later, she was being directed by Katie Mitchell in The City, at the Royal Court. At six, Wesley Nelson enrolled in the same acting workshops in Cardiff as his three older siblings; now 13, he made his stage debut last year at the National in Mrs Affleck, went on to play the young Ian Dury in the film Sex & Drugs & Rock & Roll, and returned to the National this year for the revival of Every Good Boy Deserves Favour.

These kids don't have actors in the family. Their parents have normal jobs: Jackie Castrey is a policewoman; Simon and Alison Nelson run a pharmacy; Bill Bruce works in Air Canada's customer services. All of them have to swap work shifts and even take leave to ferry their children to auditions and performances. Polly Bennett sent her son Finn to a week-long summer course at the local Young Actors Theatre (YAT) in London when he was five; four years later, he was winning rave reviews for his "no less than extraordinary" performance in Polly Stenham's Tusk Tusk at the Royal Court. "Sometimes I feel like I'm his PA," she says.

'I was almost asleep in class'

There are plenty of other disruptions. Under-16s (actors are classed as adults when they hit 16) can't stop going to school just because they're in a show: Lennie keeps up with missed lessons by going over work backstage, but Wesley, five years his senior, will spend half his weekend on additional homework when he's performing. Tiredness is another issue: Lennie usually goes to bed at 8pm, Ellie at 9.30pm, yet their curtain calls aren't until 10pm – and then they have to travel home. "When I first started in Enron, I was almost falling asleep in my lessons, because I wasn't used to it," Ellie admits.

But complaints have to be prised out of the children because for them, acting is simply a thrill. Not that any of them can explain why: their enthusiasm is as instinctive and difficult to articulate as it is boundless. Ellie gets closest when she says: "I like the attention, the fact everyone is looking at you." The kids learn from the adults, too: Harvey Robinson, who plays a policeman in Jerusalem, has been helping Lennie to twist his Londoner tongue around the West Country accent. At 13, Wesley is old enough to soak up what he sees. "You can see the way older actors work, their routines, and pick things up," he says. And all feel encouraged by the realisation that mistakes are inevitable in a live performance. "I thought older people didn't forget their lines," says Finn. "But then I saw that they did, and it boosted my confidence."

From the parents' point of view, acting alongside adults offers countless advantages. "It broadens their whole thought process," says Jackie Castrey. "It also brings about discipline: you can't mess about in the wings, you mustn't be late – all lessons that need to be learned in life." Certainly, these children appear very poised and responsible, not least when they talk of how, give or take the odd treat, they are saving their earnings (up to half what an adult earns per performance, regardless of how much or how little they do on stage) for when they are older. And they are impressively committed. Finn's YAT classes take place on a Friday after school: wouldn't he rather go home and watch TV? "Sometimes," he says, "but it's what I have to do if I want to keep on acting."

They are still obviously kids though. Ellie has an eloquent scowl, to which she treats her father when he says something she dislikes. Finn, when asked what he might do in the future other than acting, says, with exquisite vagueness: "I quite like snakes, so I might want to do something with snakes." Lennie, who has been keeping a tally of everything that has gone wrong in Jerusalem, announces with delight that "one of the actors farted on stage", wrapping his arm around his head to cover his mouth as he splutters with laughter.

Their guilelessness reminds you of what a difficult choice parents face in allowing their kids to take part in adult shows, in which expletives fly around, and the child might be unloved, injured or killed night after night. Polly Bennett would think twice about letting Finn take part in anything that involves "extreme violence", but the swearing in Tusk Tusk didn't worry her unduly: "He's heard swearing before; he knows he shouldn't use those words, but other people do and it's part of the story."

Jackie Castrey, who remembers being criticised in one review of The City for allowing her daughter Matilda to say "fuck", says: "It's not something you go into lightly. We read the script before the auditions. When she was learning the lines at home, we would miss out the swear word: she knew she was only allowed to say it on stage."

'Pretend your dad's a dragon''

Occasionally, they are required to prove their improvisatory mettle: at his first audition for Jerusalem, Lennie recalls, director Ian Rickson asked him to "pretend you were walking through a wood, and you're off to see your dad, who's a dragon, and you're quite scared". And these children seem to accept the vagaries of casting with admirable level-headedness. "I've been to auditions and been told I'm just the wrong height," says Matilda placidly. "It's a lot about luck, of being the right size, the right shape, having the right hairstyle," says Wesley, who, as someone with cerebral palsy, understands better than most how appearance can count against you.

Those with older siblings are keen to work while they can, because they know how quickly jobs can evaporate. Andrew Harries, director of YAT, says puberty and growth spurts can change a child's appearance so dramatically that they might not get cast at all for a year or two. And theatre directors understandably think twice about hiring 14- or 15-year-olds, who still require a performance licence from their local council (letters of approval are needed from the child's school and GP), plus a chaperone at all rehearsals and performances, just as if they were five, eight or 11. A 16-year-old presents none of these hurdles.

Harries points out another problem: acting as a child offers no guarantee of work as an adult, when competition for roles is even greater. Despite his success, Wesley is taking nothing for granted: he plans to take a degree in English then study at drama school. And Finn, who hopes to direct and star in his own movie one day, is already making a film with a friend: "It's kind of a cross between action and comedy. I got a bottle of fake blood and some tablets from Tusk Tusk – so we're putting those to good use."

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• Mark Rylance
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