Nudity, sexual arousal and the gouging of a horse’s eye – it shouldn’t happen to a wizard. When Daniel Radcliffe announced that he was going to make his West End debut in Peter Shaffer’s controversial drama Equus, it caused a wrinkle in his fans’ brows so deep it could be seen from space.

The 17-year-old’s name is all but inseparable from his portrayal of Harry Potter, the teenage sorcerer whose scholarly progress at Hogwarts School of Witchcraft and Wizardry has delighted millions of filmgoers and readers worldwide.

It’s hard to imagine him dressed in anything other than Potter’s owlish spectacles and wizard’s robes, but theatregoers attending the Gielgud Theatre, where previews started on Friday (16 February 2007), will see him wearing nothing at all. There will be no dialogue relating to Quidditch scores or the furtive activities of “he who cannot be named”. Instead, audiences will be greeted by a wild-eyed Radcliffe chanting: “Neckwus begat Fleckwus, the King of Spit, and Fleckwus spoke out of his chinkle-chankle”.

Strang & stranger

Memories of Radcliffe riding his broomstick will be banished by the vision of him on horseback bringing himself to a sexual climax. His casting as Alan Strang, a psychologically disturbed stable boy arrested for mutilating the horses in his care, is as far removed from his wizard-next-door image as is possible in a commercial West End production.

Equus is the story of Strang’s interviews with a hospital psychiatrist, Martin Dysart, who seeks to understand why his patient was driven to violent acts. It caused a sensation when it was first staged – at the National Theatre in 1973, then based at the Old Vic, with Peter Firth as the tormented boy, Alec McCowen as Dysart and part of the audience seated on stage – and became a box office smash in New York, where it ran for 1,200 performances. Anthony Hopkins made his Broadway debut as Dysart (with Firth reprising his role) before handing the role to Richard Burton, who would also star in the play’s 1977 Sidney Lumet-directed Hollywood adaptation (again, alongside Firth).

In this production, Dysart is played by Richard Griffiths, the Tony Award-winning actor known to Harry Potter fans as the wizard’s curmudgeonly uncle Vernon Dursley. The other principals are played by Jenny Agutter, who also came to fame young with her appearance in the 1970 film of The Railway Children and later won a BAFTA award for her performance as stable girl Jill in the film version of Equus (this time she’s playing a magistrate), and Will Kemp (best known for his starring roles in Matthew Bourne’s Swan Lake and Cinderella), playing one of the horses, Nugget.

This time Jill will be played by 24-year-old Joanna Christie, who was chosen by director Thea Sharrock and producers David Pugh and Dafydd Rogers after auditioning more than 300 young hopefuls and narrowing the list down to six finalists, who were invited back last December to read the script with Radcliffe. “It was the chemistry between them,” said Pugh after Christie had been awarded the role. “She was the one Daniel fancied the most, and that swung it for us.”

A far from normal life

Radcliffe’s casting in Equus is not merely extraordinary for being so radically against type. It’s virtually unheard of for a 17-year-old with no significant stage experience to land a leading role in the West End. His only West End credit to date was a guest appearance in the Kenneth Branagh-directed The Play What I Wrote, a Morecambe and Wise tribute acted by the Right Size team, which featured a different star every night.

But Radcliffe has had a far from normal life. His talent as a child actor did not go unnoticed by the BBC, which cast him as the young David Copperfield at the age of nine. His lottery-like success came two years later at the auditions for Harry Potter and the Philosopher’s Stone. He was paid £150,000 – a seemingly handsome figure until receipts filtered back from box offices around the world. The film grossed $975 million, making it – at that point – the second most successful film after Titanic. It is still in the all-time top four.

By the time of the third Potter film, Radcliffe had £10 million in the bank and stood to make another £5 million for Harry Potter and the Goblet of Fire. He is thought to have taken home £8 million for the Order of the Phoenix and, if he continues in the leading role for the final two installments, will have earned an estimated £42 million by his twentieth birthday.

Despite his meteoric rise and astronomical wealth, Radcliffe has not succumbed to the fate of many child stars – public displays of overindulgence and self-destructive acts of rebellion. He has been sheltered from much of the media glare by his parents (his mother, Marcia, is a casting director and his father, Alan, works as a literary agent) and by David Heyman, the producer of the Harry Potter films. Even so, he has still had an abnormal upbringing. His schoolroom has been a trailer on a film set for up to 11 months at a time, and he has been confronted with crowds of 3,000-plus screaming girls on visits to Japan, where he’s more popular than Leonardo DiCaprio or Sir Paul McCartney.

He has hung out with Jarvis Cocker and learned to play the bass with Gary Oldman, but the celebrity lifestyle hasn’t resulted in the kind of excess associated with Lindsay Lohan or Charlotte Church. The closest Radcliffe has come to rebellion is a professed fondness for Pete Doherty, the crack-smoking singer more famous for his court appearances and his girlfriend Kate Moss than his tour dates. Maybe he has a teenage crush on Moss, but Radcliffe has said he would like to play the former Libertines singer if his career merits a biopic. “That’s a long way down the line, though,” the actor said. “If we start talking specifics about doing Pete’s life, it makes him sound like he’s dead – and he’s not dead yet.”

He is also an ardent fan of punk rock, in particular the Sex Pistols album Never Mind the Bollocks. “If you look at bands who say they’re punk now, like Sum 41, and then look at the Sex Pistols and what they stood for and what they meant and what they managed to do and… well, the others are just pop music really, aren't they?”

Charm & precocious wisdom

Despite such occasional flashes of rebellion, Radcliffe remains the sort of teenager any mother would love, exuding a combination of charm and precocious wisdom. He reportedly prepared for Harry Potter and the Prisoner of Azkaban by watching the French Nouvelle Vague film Les Quatre Cent Coups to get a handle on “Harry’s feelings of hopelessness”. And while discussing his forthcoming role as Rudyard Kipling’s son in My Boy Jack, a television drama for ITV, adapted from the stage play by David Haig, he spoke about wanting to make the Great War relevant to his generation.

“For many people of my age, the First World War is just a topic in a history book,” he said. “I can’t even begin to imagine what it must have been like in the trenches, living amongst the stench of death and knowing that any moment may be your last. But I think it’s important we try to imagine the horrors these young men experienced and to never forget them.”

Although he has no stage experience in the capital, Radcliffe has already gone on show at one venerable London institution. He’s the youngest person, outside of royalty, to be the subject of a solo portrait in the National Portrait Gallery’s permanent collection. Stuart Pearson Wright, who has painted Michael Gambon and Rosamund Pike, said that he was struck by Radcliffe’s irrepressible cheerfulness and youth. “It was quite a challenge,” the artist said. “It was not that Daniel lacked character, it was just that he had an extreme openness and lack of cynicism, and it was difficult to know what to do with that.”

Radcliffe is also no stranger to musical theatre, thanks to the passion of his parents. “I remember we always used to have Chicago playing when we went to the seaside,” he said. “There’s this song in which the women go on about how they killed their husbands, which terrified me.”

So what of the future for the teenage star? “One day I would like to focus more on writing poetry,” he said in November. “I don’t see myself going to university, though. I think that’s a time for people to work out what they want to do with their lives. I already know.”

Equus will be a genuine test of Radcliffe’s versatility. If he convinces critics and audiences that he can work magic without a wand, there will be no stopping him.

Equus opens on 27 February 2007 (previews from 16 February) at the Gielgud Theatre, where its limited season continues until 9 June 2007. A version of this article appears in the February issue of What’s on Stage magazine (formerly Theatregoer), out now in participating theatres. Jack Malvern is a reporter for The Times.