Amanda Sandford, a spokesman for Ash, the anti-smoking organisation, said: "It is regrettable that he is smoking, whatever the circumstances. He is a role model for young people and if he decided to take up smoking in real life that would be of great concern.

"If they are worried about smoking and not about the fact that he's simulating sex with a young girl on stage, it makes me think that they've got their priorities wrong.

"Daniel smokes in the play. He doesn't smoke in life. It's in the script and it always has been. It is not gratuitous. In fact, it's a very beautiful scene where Alan Strang (played by Radcliffe) is with his psychiatrist. The psychiatrist offers him a cigarette and it's really the first time the man and boy bond as they talk and smoke."