The two surviving Beatles took to the blue carpet on Thursday for the London screening of a new documentary, with the film's archive footage described as "very emotional" by Paul McCartney.

"Eight Days a Week: The Touring Years" follows the band on the road for four years from their native Liverpool in 1962 through a series of US tours characterised by Beatlemania.

Appearing at the screening in London, which followed the world premier in Liverpool earlier on Thursday, McCartney said the documentary brought back fond memories.

"We're getting great memories obviously of playing with John and George.

"So that's very emotional and very special to see that again," he told reporters.

McCartney, 74, was joined at the screening by fellow Beatle, 76-year-old Ringo Starr.

John Lennon's widow Yoko Ono, and Olivia Harrison, widow of George Harrison, also attended, in addition to celebrities including Madonna.

Half a century since the Beatles played their last major concert -- at Candlestick Park in San Francisco -- Starr said their enduring popularity was "beautiful".

"People love the Beatles. We happen to be two of them and here we are," he said.

The film, directed by Ron Howard, includes previously unseen footage which shows the toll fame put on the band as they were mobbed by fans around the world. 

In one interview, Lennon said the hysteria at their performances turned Beatles concerts into "a freak show".

"The music wasn't being heard," he said. 

McCartney said he was the last of the band to decide to give up live performances. 

"We did Candlestick Park and it was OK, a lot of screaming and we didn’t enjoy the gig and we were just hustled into this meat wagon which was just like a chrome box and we are all just sliding around looking at each other thinking 'bloody hell'," he told BBC's "The One Show" on Wednesday.

Starr told the BBC they realised it was the moment to stop: "We had just had enough, we knew that was the last gig, it was time. You can only do that for so long."

The Beatles played their last live performance three years after the Candlestick Park concert, on the rooftop of their Apple Records headquarters in London.

Ahead of the screening, McCartney said he took pleasure from watching the Beatles perform.

"I think the basic thing about the Beatles is that we were a great little band," he said.

"So to see us performing as a band is a great thing, because without that, we couldn't have made the records. That was the foundation of everything we recorded."