While in Liverpool, McCartney took a trip down Penny Lane and showed Corden local landmarks including the church where he was a choir boy and his old barbershop.
During the drive, Corden told McCartney: "Your music is so full of positivity and joy and a message of love and togetherness, I feel like it's more relevant now today maybe than it's ever been".
After singing "Drive My Car" and the first song he ever wrote, a ditty called "I Lost My Little Girl", Paul explained how the genesis of "Let It Be" came to him in a dream. I felt so bad when it came out in the press - "Foo Fighters had a awful time, they hated the whole fucking thing".
As he led Corden through the home (even sitting down at the piano to sing "When I'm 64"), he told Corden how his father had critiqued "She Loves You", suggesting they replace the "yeah, yeah, yeahs" with "yes, yes, yes".
"Oh man, it got me emotional there, Paul", Corden says as the song comes to an end. Their duet left Corden in tears: "That's the power of music", said McCartney.
"From there, they visited McCartney's childhood home - which he said helps him "realize how long the journey has been" for him" - before the two drove around town again, singing one of Paul's new songs. "I remember me and my mom and dad".
'I think if my grandad was here now he'd get an absolute kick out of this'.
Setting up hidden cameras around the bar, Corden gave the regular pub-goers a surprise they'd never forget.
All the while, the two sing some of the Beatles' biggest hits, such as "When I'm Sixty-Four", "Blackbird", and "A Hard Day's Night", as well as "Come On to Me", one of Paul's two new songs, released just last June 20, from his new album Egypt Station.