I’m the only person who is allowed to say nasty things about Paul. I don’t like it when other people do so.

The thing you must remember is that I’m the Number One John Lennon fan. I love him to this day and I always did love him.

They (John and Paul) told me that they considered each other, at that time, such an integral part of each other’s influences that they were in some ethereal way writing songs together though apart.

John is a central figure in my life. I will always be grateful for having so much intimate time with him. The more distant his stuff becomes, the greater he seems. I used to do caricatures of John. He was the only person I knew with an aquiline nose. When I painted him recently, I found myself saying: ‘How did his lips go? I can’t remember.’ Then I would think: ‘Of course you know, you wrote all those songs facing each other.’

I thought John was cheating on me with Paul.

John never looked at anyone the way he looked at Paul.

John and Paul's standard of writing has bettered over the years, so it's very hard for me to come straight to the top, on par with them. They gave me an awful lot of encouragement. Their reaction has been very good. If it hadn't, I think I would have just crawled away.

With John and me on a song, if I come up with some lines which I know aren't really very good and I'm just hoping to fool him, I know I won't. 'I Saw Her Standing There' was the best example of it. I thought of the idea driving home from a concert in Southport. I had 'She was just seventeen,' and then, 'Beauty queen.' I knew this was rubbish, and that I'd put it down just because it rhymed. When I showed it to John, he screamed with laughter, and said 'You're joking about that line, aren't you?' And I realised that, in fact, I was, and we changed it.

The way that Lennon and McCartney worked together wasn't the Rodgers-and-Hart kind of collaboration. It was more a question of one of them trying to write a song, getting stuck, and asking the other: 'I need a middle eight. What have you got?' They were both tunesmiths in their own right and would help each other out as the need arose.

Paul provided a lightness, an optimism, while I would always go for the sadness, the discords, the bluesy notes. There was a period when I thought I didn't write melodies, that Paul wrote those and I just wrote straight, shouting rock 'n' roll. But, of course, when I think of some of my own songs – "In My Life", or some of the early stuff, "This Boy" – I was writing melody with the best of them.

One of us might think of a song completely, and the other might just add a bit. Or we might write alternate lines. We never argue. If one of us says he doesn't like a bit, the other agrees. It just doesn't matter that much. I care about being a song writer, but I don't care passionately about each song.

When I write, there are times -- not always -- when I hear John (Lennon) in my head, ... I'll think, OK, what would we have done here? and I can hear him gripe or approve.

I said that [playing down how much he and McCartney collaborated], but I was lying.... We wrote a lot of stuff together, one on one, eyeball to eyeball.... In those days we absolutely used to write like that — both playing into each other's noses.

He provided a lightness, an optimism, while I would always go for the sadness, the discords [and] the bluesy notes.