Despite our best efforts, the Third Man charms his way past "friends in security" and corners Dave and me in the garden
at No 10. He carries two signed copies of his autobiography which, with maximum show, he hands over to us.

“Believable," he says.

“Sorry?" says Dave.

“Your shirt is believable."

“My shirt is what?"

“Believable."

The Prime Minister and I exchange a look.

“It's as if I've never been away," says Mandelson, mistaking our bafflement for encouragement and sitting down uninvited. "I'm guessing you called me in to advise you on how to detoxify the tsunami of Brokeback innuendo that is threatening to derail the project before . . ."

I dim out and speed-read the book to see if his prose style is any easier to bear. It is not. Dave, meanwhile, smiles and stares placidly at our former nemesis. It is a gift he has developed swiftly since assuming power. The gift of appearing to care. Now all he has to do is remember people's names and we'll be away at the races.

While neither of us has been listening, the one-time first secretary of state has changed gear from adviser to anecdotalist: ". . . funnily enough I happened to be sitting in this very chair next to TB just after we had won our first landslide and GB stormed in and shouted, 'This is frankly unacceptable, PM,' and I said, 'Now, now, Gordon,' and Tony said, 'I think he's talking to me. From now on only one of us can be PM,' and GB thought TB was talking to him and the rest . . ."

I am the first to crack.

“That's fascinating, Peter, but if you'll excuse us, David and I must start packing our trunks for the summer holidays, so to speak."

“Of course, of course. It's been a pleasure." He rises and is halfway out of the garden when his own memory stops him in his tracks. "The extraordinary thing was that no one ever seriously referred to Neil as NK. We tried . . ."

“The trunks, Peter, we must attend to our metaphorical trunks." He finally takes the hint and Dave celebrates his exit by tossing his book into the recycling bin.

“Bingo. Isn't it astonishing, Gidders, that we used to quake at the mere mention of his name?"

“And now he's just another tired old celeb with a book to plug."

“A desperate ragbag of tittle-tattle. Surely it was drummed into him at school that you don't tell tales."

“I'd be surprised if he ever went to that kind of school, Prime Minister."