By RICHARD SIMPSON

Last updated at 21:05 15 July 2007

When Laurence Olivier stayed in Hollywood at the start of the Second World War, he was accused of lacking patriotism. Many said the actor should have joined up.

But in reality he was working as a secret agent to persuade influential Americans to support Britain. A biography reveals that in 1940 he was enlisted into the Special Operations Executive by film producer Alexander Korda.

Michael Munn, author of Lord Larry: A Personal Portrait Of Laurence Olivier, said: "Churchill recruited Alexander Korda to set up offices in America which were a front for the Special Operations Executive and MI5. Korda then recruited Olivier."

He said Noel Coward told him: "It was down to Alexander Korda to tell Larry that Winston Churchill was not asking but telling him that his country expected him to do his duty."

David Niven told Munn: "If German agents realised, they would have gone after him."

Olivier returned to Britain in 1941 and joined the Fleet Air Arm, completing 456 flying hours.