Harry Potter actor Sir Michael Gambon retires from the stage because he can no longer remember his lines

The performer called the decision to leave his live audience 'heartbreaking'

(Anthony Woods )

Sir Michael Gambon has announced his retirement from the stage because he can no longer recall his lines.

The 74-year-old actor, who played Albus Dumbledore in the Harry Potter film franchise, became so worried by his memory loss that he began performing with an earpiece linking him to a stage prompt.

Michael Gambon (left) with co-stars at the New York premiere of Harry Potter and the Half-Blood Prince in 2009

“It's a horrible thing to admit but I can't do it. It breaks my heart,” Sir Michael told The Sunday Times Magazine.

He realised his time in front of a live audience was up, he continued, after an audition for a new West End play, during which a girl in the wings read his lines for him. He was replaced by Richard Griffiths.

The only roles he could play on stage since then were bit parts with one or two quotes to deliver.

“You know, the sort of part where he comes on and says a few words,” he said.

“A role that’s played for laughs – like when the phone goes, he doesn’t know where it is.”

He previously spoke of undergoing tests for Alzheimer’s disease. However, after a second opinion produced negative results, it became apparent is problem was down to the natural process of aging.

Sir Michael became a household name when he starred in BBC crime drama The Singing Detective in 1986.

The sleuth hurts: Michael Gambon as Philip E Marlow and Joanne Whalley as Nurse Mills in 'The Singing Detective' from 1986 (BBC)

Following the death of Richard Harris in 2002, he took over the role of Hogwarts headmaster Dumbledore in the third Harry Potter film, Harry Potter and the Prisoner of Azkaban.

“Richard Harris had just died and they approached me and I decided to play it with a posh Irish accent, rather like Harris,” he continued.

“I’d never seen any of the previous films but working on the series was huge fun - and for lots of dosh.”

Before he became an actor, he said, he had trained to become an engineer.

Michael Gambon, left, and Richard Dormer in ‘Fortitude’ (Sky Atlantic)

However, he still has some time left on the small screen. Sir Michael will next appear in Scandinavian drama Fortitude at the end of February.

He will also feature in the BBC adaptation of JK Rowling’s Casual Vacancy, above.