“I’ll just be a couple of seconds, I’ve got a patient in here,” says Sir Paul McCartney, poking his head round his office door.

He disappears again, leaving you to nervously scan the books in the waiting room – three dictionaries, some Taschen art folios, a few dozen Beatles reference works and a surprising number of Jamie Oliver cook books.

Minutes later Sir Paul reappears, ushering out his “patient”, who turns out to be one of the many assistants at his plush, five-storey office in Soho.

“Take the pills three times a day,” he quips. “You might feel a little drowsy at first.”

As he beckons you in, the star begins fussing around the room, making small talk (“You’re from Belfast? I thought I detected that lovely little accent”) and straightening up his picture frames.

“Slight obsession,” he says. “What do they call it? Obsessive compulsive disorder. Disorder! I think it’s the opposite. I think it’s order.”

All this kerfuffle is designed to put you at ease.

The most famous musician on the planet is fully aware of the effect he has on lesser mortals and, 56 years after Love Me Do, he’s become adept at soothing people’s nerves before they collapse like a bouncy castle in a power cut.

You can see it in practice on his recent episode of Carpool Karaoke, when the 76-year-old is mobbed by fans outside his childhood home in Liverpool.

Slowly but purposefully, he walks through the crowd – shaking hands, saying hello, acknowledging everyone; but constantly moving forward until he reaches his car and, with one final wave, slips inside.