BOLTON actor, Sir Ian McKellen, joined Dame Judi Dench in unveiling a blue plaque commemorating the London home of stage and screen star, Sir John Gielgud.

The English Heritage plaque at number 16 Cowley Street in Westminster marks the brown brick Georgian townhouse where Sir John lived for 31 years, from May 1945 to February 1976.

The actor dominated the British stage throughout most of the 20th century and appeared in more than 100 films in a career which spanned more than 75 years.

He was renowned for his Shakespeare performances, and was also one of only a handful of people to receive an Oscar, a Grammy, an Emmy and a Tony award.

Dame Judi paid tribute to her long-time friend and colleague, saying she had been "devoted" to him since he gave her support when a theatre director had been making things difficult for her.

"I worked with John Gielgud in The Cherry Orchard, when I played Anya and he was Gaev.

"The director, Michel Saint-Denis, gave me a very hard time and almost destroyed my confidence.

"But at one rehearsal, as we exited at the end of Act 1, Sir John said: 'Oh, if you'd been doing that for me in one of my productions, I'd have been delighted.'

"I was devoted to him for evermore.

"If you want to know how to speak Shakespeare, Sir John and Frank Sinatra will teach you.

"One presented the whole arc of a speech, and the other presented the whole arc of a song."

Professor Ronald Hutton, chairman of the Blue Plaques panel, said: "Sir John Gielgud was one of the finest English actors of his generation.

"Beloved by his peers, he is remembered for his complete mastery of Shakespeare and is thought by many to have been the greatest Hamlet of the 20th century.

"Gielgud was always particularly fond of his house on Cowley Street and I am delighted to celebrate his long and varied career with a new English Heritage blue plaque here today."

Born in South Kensington on April 14 1904, Gielgud made his professional debut in 1923 as the Poet Butterfly in Karel Capek's The Insect Play at the Regent.

He was in work almost constantly from that moment until his final role in Samuel Beckett's Catastrophe at the age of 96, with acclaimed theatre performances in plays by Oscar Wilde, Anton Chekhov, Harold Pinter and Alan Bennett, as well as many films.

Cowley Street was Gielgud's home for some of the most important moments of his life, including receiving a knighthood for services to the theatre in 1953.

But it also encompassed a darker period around the time of his arrest in 1953 for a homosexual offence - one of a number of high-profile cases which were an impetus for the decriminalisation of male homosexuality in 1967.

The blue plaques scheme, taken on by English Heritage in 1986, has been running since 1866 to commemorate the notable people who lived and worked in buildings in London.