Sir Derek Jacobi says he had “no idea” he was breaking the heart of friend and colleague Sir Ian McKellen, who once had a crush on him when they were studying together at university.

The actor was talking about his lifelong friendship with the Lord of the Rings star to BBC Radio 5 on Monday afternoon.

“He had a candle for me,” Sir Derek, 74, added: “I had no idea I was breaking his heart.”

The pair have been friends since they met at Cambridge in 1958. Sir Ian, 74, previously spoke of how he had been “desperately in love” with Sir Derek when he was 18, describing it to the Advocate in 2001 as a passion “that was undeclared and unrequited.”

Both actors star in Vicious, a sitcom based on two gay squabbling ex-thespians who have been together for 50 years.

The show received mixed reviews when it aired for six episodes earlier this year.

Several TV commentators criticised Vicious for pandering to old fashioned gay stereotypes

In June, comedian Barry Cryer branded it “positively homophobic”.

However, Sir Derek has hit back at the critics and suggestions that as an esteemed Shakespearean actor – he, along with Sir Ian McKellen, should have “disdain” for a mainstream television sitcom.

“That’s the glory of being an actor: We do anything, we are jobbing actors”, Sir Derek told presenter Richard Bacon.

He said to be given the chance to do something “totally” different was “wonderful”, and that his character, Stuart, has some of his own personality.

Sir Derek also mentioned how he insisted that the show’s original title ‘Vicious Old Queens’ was shortened to just ‘Vicious’, as it was too “on the nail.”

Despite ending its run in April – with less than half of the 6 million viewers that it started with – ITV recommissioned the sitcom for another series in August.