Simon and Garfunkel may have started, in the words of Alan Yentob, as two Jewish nebbishes from New York but by 1970 they were on top of their game.
The album, Bridge over Troubled Water, was their Sergeant Pepper, a supreme moment of creativity that, poignantly, was also their last recording together. However, unlike the Beatles, who were disintegrating acrimoniously at around the same time, the contemporaneous footage reveals Paul and Art still having a ball. As Garfunkel recalled: "There's nothing like hit records - it puts you in such a good mood."
What fans of the duo might not have realised was that they had their own George Martin, in the shape of Roy Halee who went to extraordinary lengths to capture the right sound - for example, recording one song in the chapel of Columbia University for its echo.
The film gave an insight into Simon's songwriting genius, which occasionally took even him by surprise. As the chorus to Bridge over Troubled Water came to him, he realised that it was an "exceptional song" - far better than he was normally capable of, he admitted.
Imagine also gave a flavour of the times. The duo made a documentary in 1970, setting their music to footage of America's poor. It was dismissed as "too humanistic" by its commercial sponsor, AT&T, who pulled out. Not that this stopped these two cocky, thoughtful Jewish boys from having the time of their lives. And watching them have fun was pretty enjoyable, too.