As Dumbledore might have said to Harry Potter, pay attention, this is complicated.

Potter film star Daniel Radcliffe, 18, wowed his wizard fans this year by appearing naked as disturbed teenager Alan Strang in Peter Shaffer's Equus in the West End.

During the production he started a romance with Laura O'Toole, 22, the stand-in for the actress playing Jill, the stable girl who seduces Strang in the play's pivotal nude love scene.

Now, as Radcliffe plans to take Equus to Broadway, O'Toole is to disrobe in another, British touring production of the play - opposite singer Lily Allen's younger brother, 22-year-old Alfie.

The production does not open at Chichester Festival Theatre until February, but Allen and O'Toole have already bared almost all for a promotional picture seen here and have reportedly struck up a close friendship.

A source said: "They haven't begun rehearsals yet but they are getting to know each other and they seem terrific together." Hearing this, Radcliffe may reflect that life can be as troublesome for a young actor as for a young wizard.

His appearance in Equus was seen as an attempt to break out of his squeaky-clean Potter image. Allen, however, has a rather less wholesome reputation.

Keira Knightley, who co-starred with him in Atonement, joked recently that he had a penchant for marijuana and sister Lily immortalised him in her song Alfie, which includes the lyrics: "My little brother's in his bedroom smoking weed, I tell him he should get up 'cos it's nearly half past three."

Perhaps understandably, producer David Pugh tested Allen's commitment. "We arranged an 8am breakfast at the Wolseley with Peter Shaffer and Alfie to see if he was still a stay-in-bed-all-day kind of boy," he said. "I think he was the first to arrive."

Allen and O'Toole will be appearing alongside Simon Callow and Avengers star Linda Thorson. Radcliffe will be reunited in New York with his Equus and Potter co-star Richard Griffiths... probably wishing he had Harry's magic powers to reunite him with his girlfriend.