During his first days in office, somebody should let the new mayor of London know that he must change the announcements on the Tube. They annoy his father Stanley, a classical scholar.

“You get on the Underground train and what do you hear?” fulminated Johnson Sr. “ ‘This train terminates at Stanmore’. What complete garbage. Terminate is a transitive verb. You ‘terminate’ someone’s life. I will ‘terminate’ this conversation.”

I don’t think so. Like his son Boris, Johnson Sr loves to talk. He will engagingly canter into almost any topic: his six children, his two wives, the letter he sent to Churchill at the age of 10, his views on Antarctica, Barack Obama and the rest. There are few areas on which Stanley will not be drawn.

At 67 he is longing to talk about all the things he has done in his life – the environmental campaigning, the political ambitions, the novels and the journalism. But in some ways he is content to tread in the footsteps of his son. Last week, with typical élan, Stanley announced that David Cameron “will lead the Tory party into the promised land” and that he, Stanley, would be happy for the Conservative party to consider him for Boris’s soon-to-be-vacant parliamentary seat at Henley.

He even looks like Boris: the same shock of platinum hair, the same astonished gaze at the world, the same garrulous nature with its alarming tendency to veer off into the danger zone of the politically incorrect.

“Got to avoid gaffes,” said Stanley. “The Johnsons are now officially gaffe-proof.” For how long? “For ever.” He paused: “Although I am now the Old Gaffer, I suppose.”

Of course you are, even though you were only 23 when Alexander Boris arrived. Do you find that irksome?

Stanley opens his arms out wide: “Politics is one career, journalism another, environmentalism another, civil service a fourth.” Four out of his six children work in fields which Stanley claims he had already conquered a long time ago, so he is in no danger of being outclassed.

“If I felt that politics was the only column of achievement, then abso-harry-lutely, Boris has wiped the floor. But there are other columns that are important to me. My second son Leo is an environmentalist. I have won the Greenpeace prize for the environment. Boris and my daughter Rachel have both written novels. I have written nine novels. And I am the only one who has had one made into a film. With John Hurt in the title role.”

Blimey, Sunday lunches must have been tough. Even though the Johnson children are all in their middle years, their father cannot help wanting to outdo them. “I still like to feel a bit competitive and would like to feel at least as good as them,” he said happily.

He reminds me that he was elected an MEP when Boris was 14: “Yes, it’s true Boris helped me in that election. On the 4th of June party at Eton he and Leo went around the Rolls-Royces slapping Vote Johnson stickers on the hampers.”

Interestingly, Boris’s scholarship to Eton is the only element of the recent media onslaught that makes his father bridle. “It’s quite funny how this has been misrepresented,” he grumbled. “Winning a scholarship is a matter of honour. It wasn’t because we couldn’t afford the fees.”

Did that pique him? “Yes, because it makes people think I couldn’t have afforded the fees. Well, of course I could.” All six of his children went to public school and then on to Oxford or Cambridge and, he tells me with pride, almost all of them were classicists. This, in Stanley’s view, is the key to their success.

For Stanley, the study of Latin and Greek will set you up for the rest of your days. “Most of my confidence comes from knowing I was a jolly good classicist,” he said. His school days were clearly crucial: “I went to Sherborne. A fine, tough, rugger-playing school.

“I was head boy and vice-captain of rugger. Whenever I walked through the school, 660 boys stood to attention and took their hands out of their pockets.”

That must have been quite a feeling, I comment. “The head boy was also allowed to have a moustache, carry a cane with a silver top, and I’m not sure he wasn’t allowed a car.” No wonder this man feels able to lord it over his children. In his head he is still carrying the silver-topped cane.

He trots off to fetch his literary output and comes back with three examples. They all have glorious 1970s jackets.

“There,” he said, throwing one, a political thriller, on the table. “The Commissioner. I got £50,000 when it was made into a film.” He shows me another: “It’s about the first black president of the US. And this!” He wields a paperback sporting the title Tunnel in giant black letters: “It was about the Channel tunnel. Written years before the tunnel was actually built.”

At Oxford (he went to Exeter College on a classics scholarship) he won the Newdigate poetry prize (also won by Oscar Wilde). Stanley dashed off the winning poem (with 100 or so rhyming couplets) at midnight before the deadline at 9am the next day.

Later he married and began a family, but claims to have had no interest in parenting. “My line on parenting has been very straightforward throughout,” he said. “It’s too important to be left to parents.”

If there is an aphorism to be invented, a quote to be found or a witticism to be cracked, Stanley will deliver. Whereupon the original issue will be defused, conquered and left behind because it has become tamed by Johnson-speak.

Does he feel embarrassed to be seen as hanging on to his son’s coat-tails, I ask, tilting at Henley. He kicks off with a side-swipe from Hamlet: “Should one be deterred from having a crack at things because there are some slings and arrows?” – and continues with Tennyson: “Some work of noble note may yet be done, / Not unbecoming men that strode with Gods”.

In other words, buzz off with your impertinence.

All right, let’s talk about family life. Why did he split from his first wife Charlotte, an artist now living in New York? “It seemed like a good idea at the time,” he quipped. Had he been entirely faithful to Charlotte? At which point the twinkling wit comes to an abrupt end. “These questions are not good,” said Stanley. “I was wholly faithful to Charlotte . . .

in all important respects.” What a fascinating reply. Could this be the type of conversation that his notoriously unsteadfast son might have had once or twice around the kitchen table in the mayoral Islington home?

We move on to a family photograph album, which Johnson shows me with glee: “Look, there I am in a fez with my Turkish cousin . . . look, there is Michael Heseltine . . . look, a Spectator party . . .”

Oh, look, and there is a snap of Petronella Wyatt, Speccie columnist and former mistress of Boris, in the family album with her name written beneath the picture. “I have no idea what that picture is doing there,” he said, suddenly flustered. “No idea whatsoever. I’ve never seen it before and I cannot speak about that.”

Stanley isn’t one for sulking, however. Get him back on to his favourite subjects – himself and his famous son – and we soon return to Latin quips and twinkly jokes. “I still want to do things in my own right. I have absolutely no idea what Central Office might think about having another Johnson [standing for Henley],” he said. “If it doesn’t work there are plenty of other things to do.”

After years of disappointing struggle against Labour, Tories of the Johnson mould, it seems, have their brio back.

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