"I’d been listening to a CD of sea shanties, and Youth runs a folk label called Butterfly," he begins.

"They put out these compilations called What The Folk, so he’d sent me them. As a result, Travelling Light is a folky sea shanty, and we took it from there."

Next up was raucous opener Nothing Too Much Just Out of Sight, which sounds like an updated version of Helter Skelter, from The Beatles’ White album.

"It was something an old friend of mine in the 60s, Jimmy Scott, used to say," Sir Paul says.

"People were always saying things like ‘It’s too much, man, too much,’ and Jimmy would come back with ’Nothing too much just out of sight’. I told that to Youth, and he said ’Great, let’s have it’."

It’s not the first song Jimmy sparked off, either.

"I’d meet Jimmy and say hi, and he’d say ’Ob-la-di, ob-la-da, man, life goes on,’ so he was the inspiration for that song too," he says, referring to The Beatles’ 1968 track.

But why The Fireman? Why not just Sir Paul McCartney and Youth? It seems that surname can be something of mixed blessing.

"It can get in the way sometimes," he says. "Your reputation walks ahead of you.

"Think of Sgt Pepper, that was the idea behind that album, too."

Sir Paul has a habit of doing this. Just as you’ve gotten over the fact you’re talking to a quarter of The Beatles, and, as the Guinness Book Of Records states, the most successful musician and composer of all time, he throws in a reference to knock you off your feet. We talk about Get Back being "just a jam" and says "It’s like I used to say to John," once or twice too. That’ll be John Lennon, then.

It also happens when the conversation might not be going as he wants, or there’s a lull in the chat. Whatever, it’s an effective tool to have in the arsenal.

"When we made that album, we became those characters," he continues. "I mean, you’re not stupid, so you’re not really fooling yourself, but it’s enough of a trick to make you look at things differently.

"With Electric Arguments, I wasn’t stepping up to the microphone thinking ‘This is a Paul McCartney vocal, this must be a certain way’ – I was thinking ‘This can go any way, because this is The Fireman, and he can do anything he wants’."

Despite having passed the 64 years he once mused upon in a Beatles song, Sir Paul clearly has no intention of slowing down.