Beatles songs, Birthday

PAUL 1968: 'What happened was 'The Girl Can't Help It' was on television.
That's an old rock film with Little Richard and Fats Domino and Eddie Cochran and a few others… and we wanted to see it, so we started recording at five o'clock.
And we said, 'We'll do something, We'll make up a backing track.' So we kept it very simple – twelve bar blues kind of thing.
And we stuck in a few bits here and there in it, with no idea what the song was or what was gonna go on top of it.
We just said, 'Okay.
Twelve bars in A, and we'll change to D, and I'm gonna do a few beats in C.' And we really just did it like that… random thing.
And we came back here to my house and watched 'The Girl Can't Help It.' Then we went back to the studio again and made up some words to go with it all.
So this song was just made up in an evening.
Umm, you know.
We hadn't ever thought of it before then.
And it's one of my favorites because of that.
I think it works, you know, 'cuz it's just… It's a good one to dance to.
Like the big long drum break, just 'cuz, normally we might have four bars of drums, but with this we just keep it going, you know.
We all like to hear drums plodding on.'

JOHN 1972: 'Both of us (wrote it.)'

JOHN 1980: ''Birthday' was written in the studio.
Just made up on the spot.
I think Paul wanted to write a song like 'Happy Birthday Baby,' the old fifties hit.
But it was sort of made up in the studio.
It was a piece of garbage.'

PAUL circa-1994: 'We thought, 'Why not make something up?' So we got a riff going and arranged it around this riff.
So that is 50-50 John and me, made up on the spot and recorded all in the same evening.'