Sir Ian, 63, a key figure in the gay rights community, said he was convinced that Shakespeare was homosexual because of his depiction of gay relationships. The actor said: “Did he sleep with another man? I would say yes.”

It was clear from examination of his plays that Shakespeare had a close understanding of gay relationships. “Look to where it matters: his work, where Shakespeare certainly writes about gay people.

“One part, which I want to play, is Antonio in The Merchant of Venice. His first line is ‘In sooth, I know not why I am so sad’. The audience knows that it’s because his boyfriend has come to him to borrow money to get married.”

Sir Ian said that the play was built around the love triangle betwen an older man, a younger man and a woman. “The Merchant of Venice centres on how the world treats gay people as well as Jews.”

Anne Barton, a fellow of Trinity College, Cambridge, and an expert on Shakespeare, disagreed. “Ian is barking up the wrong tree on this,” she said.

“I don’t think for an instant that Shakespeare slept with a young man. You won’t find an academic consensus that Shakespeare was gay.”

The discovery last year of a portrait of Shakespeare’s patron, the third Earl of Southampton, apparently dressed as a woman reinvigorated the argument that the pair had a sexual relationship. But Professor Barton said that Shakespeare’s Sonnet XX, believed to have been written to the earl, indicated that their relationship was cerebral than sexual. The poem concludes “But since she (Nature) prick’d thee out for women’s pleasure,/ Mine be thy love and thy love’s use their treasure.”

Shakespeare’s exploration of the relationship between Antonio and Bassanio in The Merchant of Venice was important, but it was significant that Antonio was left on his own at the end, Professor Barton said. “When the couples go off at the end, there’s no place for a threesome. Antonio has to shrug his shoulders,” said.

Sir Ian admitted that the evidence for Shakespeare’s sexuality was circumstantial, but said that the “immense” complexity of sexuality in his comedies confirmed his belief. “We really don’t know for sure if Shakespeare was gay and it is not especially important. But was he interested in sexuality? Absolutely. Did he know about it? Better than anybody.”

Diane Purkiss, of Oxford University, another Shakespeare scholar, said that inferring Shakespeare’s sexuality from his characters in The Merchant of Venice was like inferring that he was Jewish. “What we do know about Shakespeare’s life indicate that he was heterosexual,” she said.

“It is true that there was a culture of being attracted to young boys in 1690s London, but it is very difficult to know whether he was part of it.”

Shakespeare’s homoerotic poetry did not necessarily indicate that he was homosexual, she said. “We know that there was a culture of writing homoerotic poetry at the time,” she said.

Sir Ian acknowledged that Shakespeare was married to Anne Hathaway and had three children by her, but said that the playwright’s decision to leave her to live in London showed his lack of interest in her. “He was living very far away from his wife,” he said. “What does that tell you."