SIR Ian McKellen has hit out at a Hollywood director's suggestion that homosexual actors should keep their sexuality hidden from the public. The openly gay X-MEN star, 67, is appalled by the unnamed film-maker's belief that homosexual actors can never convince audiences playing heterosexual characters. He says, "Acting is acting and if that were true Heath Ledger wouldn't be allowed to be in Brokeback Mountain because he's presumably a happily married young man who doesn't have a gay bone in his body. "And couldn't you just tell?"