Idris Elba has described the ‘surreal’ moment when he heard Nelson Mandela had died, during the world premiere of his biopic about the statesman.

News of the former South African president’s death emerged a fortnight ago, midway through the screening of the film Mandela – Long Walk to Freedom, which stars Idris.

In an interview with Radio 2’s Chris Evans, he said that the Duke and Duchess of Cambridge were in tears.

He described it as ‘undoubtedly one of the strangest – and most beautiful – moments of my career’.

Idris explained: “Literally halfway through the film Mandela had passed and there was sort of a slight buzz around the auditorium. Interestingly, the Duchess, Kate, sort of turned to me and looked at me as she had her phone and I wondered what was wrong with her because she looked quite emotional, but the film’s very emotional.

“And my girlfriend looked at me and handed the phone and I looked down and Mandela had passed and it was on a website. It was just the most surreal moment. I looked back at Kate and Prince William and they were just in tears with me. It was just odd. Very odd.

“There’s a moment in the film and I play older Mandela and he says this one line and it is ‘just open the gate and let me free’ – and I kid you not, that that was the one line when we heard the news that was on the screen.”

He and the film’s producers decided he should make an announcement to guests who had gathered within the Odeon Leicester Square cinema in London.

“It only felt appropriate to say what had happened and honestly there was an audible gasp in the auditorium. Some people didn’t know, they had their phones off. It was just surreal.

“It was very odd, after seeing the credits and I walk on stage. They were giving me a nice round of applause but it was just this moment where I had to say please sit down, and announcing the official speech from president Zuma of South Africa. It was just weird.”