The song's composers are officially listed as McCartney and late Beatle John Lennon, but Martin claims McCartney added Lennon's name to the songwriters list, despite the IMAGINE singer having no involvement in the melody.
He says, "We didn't know what to do with it. It was such a soppy tune, so I went away and wrote a score for a string quartet to go with it.
"Two days later I was rehearsing it and Paul McCartney walked in. He'd never seen a score before, and he said, 'It hasn't got my name on it.'
"So I handed him a pencil and he signed it.
"He wrote John Lennon's name too - although he had nothing to do with it - and added Esquire to mine."