Harry Potter star Daniel Radcliffe was forced to change the name of his onstage steed when hit play Equus transferred to Broadway from London's West End - after realising the horse was named after a U.S. condom brand.

In London, the young actor's equine co-star was called Trojan, but Radcliffe knew that name would have to go when the play started a run in New York.

He explains, "One of the horses in the show was called Trojan. I say, 'What's his name?' and the answer is 'Trojan... and you can stroke him.'

"We went into the rehearsal room, and I didn't feel that we could say that, because all the American tourists were laughing, so we decided to call it (horse) Hero."