The pair became a prolific songwriting partnership and MCCartney admits he still calls on Lennon's spirit to help him make tune choices in the studio.
He tells Rolling Stone magazine, "If I'm at a point where I go, 'I'm not sure about this', I'll throw it across the room to John. He'll say, 'You can't go there, man'. And I'll say, 'You're quite right. How about this?' 'Yeah, that's better'.
"We'll have a conversation. I don't want to lose that."
Lennon died in December, 1980.