In 1974, Elton John was joined on stage in New York's Madison Square Garden by John Lennon.

Turns out Lennon was there due to a bet the pair had made between them. Elton John who at the time was a 'hit making machine' contributed to Lennon's record "Whatever Gets You Through the Night" with vocal harmonies and piano – on one condition. If it went to number one in the US, Lennon would have to perform the song with him onstage.

photos by Steve Morley/Redferns12