Joan Collins left the Beatles’ last concert because of the smell of marijuana

The performance was filmed by their documentarians, who were filming the Let It Be movie to coincide with the release of their final album of the same name. Although they were threatened when they started playing, the police officer who was there that day has now laid down the truth.

The Dynasty actress, 90, had a perfect view when the Fab Four put on the impromptu concert above their Apple Corporation HQ in London, on January 30, 1969.

As crowds gathered in the streets below, John, Paul, George and Ringo played for 42 minutes before the Metropolitan Police arrived and told them to turn down the volume.

But Dame Joan – who at the time was dating Apple Corps president Ron Kass and regularly hung out with the legendary band – had not stuck around.

She recalled: “I remember going up to the roof...for their last concert, when they played Get Back, but leaving before I succumbed to a contact high from all the marijuana being smoked.”

McCartney even started poking fun at the officers during the performance. He changed the lyrics to one of the songs to hit out at the police trying to do their jobs.

He improvised some of the lyrics after he locked eyes with Dagg and his fellow police officers.

He reportedly crooned: "You've been playing on the roofs again / And you know your momma doesn't like it / She's going to have you arrested."

Billy Preston recalls that it was John Lennon who had the idea to stage the concert on the roof of Apple headquarters. Lindsay-Hogg says it was his idea. Others attribute it to Ringo Starr. The concept sounds inspired, but in retrospect it speaks less to creativity and more to laziness.

A few minutes before the concert was due to start, the band huddled in a small vestibule at the top of the stairs. They had cold feet. "George didn't want to do it, and Ringo started saying he didn't really see the point," says Lindsay-Hogg. "Then John said, 'Oh, fuck it — let's do it.'"