Stanley Johnson talks I'm a Celebrity, growing old disgracefully – and whether son Boris will make Prime Minister

Johnson senior may be 77 now but, of the two, he’s in better shape. He brushes that ridiculously luxuriant family fair hair, for a start. And the plus side of the torture chambers of reality television, as I know myself, is that being starved is just dieting under duress. He lost eight kilos in the jungle [doing I’m a Celebrity! Get Me Out of Here… in 2017] and is keen to keep it off.

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When we meet for lunch at the Garrick, the finest gentleman’s club in London and the world headquarters of bibulous bufferdom, he causes a sensation by asking for a straight soda water. The clatter is the sound of monocles falling on to the parquet floor; the dull thud is the waitress, who’s fainted.

Stanley has packed a lot into 77 years. Trainee spy, international civil servant, politician, author, environmental campaigner, now reality TV star and, as one downmarket newspaper put it, “the toff among the tarts”. He absolutely loves it, glories in it, and wants to keep on going – for ever, if possible. His energy and enthusiasm are, frankly, exhausting to watch.

“If you’re going to hit the buffers – and we all are,” he says, looking at me meaningfully over his soda water and my large sauvignon blanc, “you may as well hit them at full speed!”

All of which might have caused a bit of a problem with his latest venture into reality TV, The Real Marigold Hotel. After all, the conceit of the series, churning along in the wake of the successful feature films, is to take a bunch of semi-cherished oldies out to India in search of an exotically different kind of retirement – and retirement is absolutely the last thing on his mind. He quotes at length from Tennyson’s Ulysses – I forgot to mention he’s a poet, too – and says his ambition is:

To sail beyond the sunset, and the baths

Of all the Western stars, until I die.

“Old Tennyson had it right,” he says. “You’ve got to bloody well keep going".

You have to give it him to come out with this stuff on one glass of soda water. I looked it up afterwards and found Tennyson was nearly two centuries ahead of his time and had neatly skewered the nature of Stanley’s 21st-century television fame in the same poem.

I am become a name;

For always roaming with a hungry heart.

Stanley is enough of an old reality hand not to get too carried away about a programme until he’s actually seen it. After all, you can spend weeks not realising you are coming across as a petulant, self-centred jerk – or them doing it for you in the cutting room. But he obviously had a good time and he can’t stop his enthusiasm going into hyper-drive.

“It was totally wonderful,” he says. “I absolutely loved it.” A lot of this was down to the company of “some stylish ladies”, including the former newscaster Selina Scott and the actresses Susan George and Stephanie Beacham. Stanley, a self-confessed ladies’ man – “in the nicest possible way” – was evidently in his element.

By happy coincidence the “very, very stylish ladies” shared his interest in animal welfare. Stanley has a bee in his bonnet about animals – in fact, bees are possibly the only animals he’s not energetically campaigning to preserve. He and Scott spent a lot of time talking about goats, apparently.

The other attraction was retracing a famous journey he made with an Oxford fellow student, Tim Severin, and a cameraman, Michael de Larrabeiti, when he was an undergraduate in 1961. The three of them borrowed a couple of BSA Shooting Star motorbikes with sidecars and, with a total budget of £200, set off in the steps of Marco Polo and his 13th-century journey to far-off Cathay. It was a heroic shambles from the start. “As soon as we got to France we realised the sidecars were on the wrong side of the bikes. Didn’t give it a thought.”

They never got to China. One sidecar fell off in Yugoslavia, the other in Turkey. They smashed up one of the bikes in what was then Persia and rode, three up, on the remaining bike for 2,500 miles, through the Khyber Pass and beyond.

There’s a picture of them at the Gateway to India in Bombay. De Larrabeiti is on the luggage rack, Stanley steering – “I was the only one strong enough to hold the bike up.” Two are wearing helmets, but Stanley is bare-headed.

“Everywhere we went in Afghanistan the tribesmen gave us mutton stew and the only thing we had to carry it in was my helmet.” The haystack of hair was probably protection enough.

He looks back on his younger self and sighs. “The things you do when you’re young – now, you just think, ‘That was a bit brash’.

“We had a picnic once on top of a giant statue of Buddha, spread out on its head, 165 feet above the ground overlooking this amazing valley.” He pauses. “Christ, did we really behave like that in the 60s?”

Severin wrote a book about their adventures, Tracking Marco Polo, and went on to become a famous explorer and travel writer. Stanley became a spy. “Hush, hush. Officially the Foreign Office, but, you know, MI6 they call it now. The most intensive clandestine training known to man.” The only thing he can remember is re-tying his shoes a lot – “Best way to tell if anyone’s following you.” I say that explains why James Bond always wears lace-ups, and he smiles a secret smile.

He never did get a licence to kill. He went off to the World Bank instead, got married and had Boris. He’s obviously hugely proud of him. “He’s an absolutely massive talent. He knows an enormous amount about a whole lot of things – not just Greek and Latin, though that’s part of it.”

Though scrupulously supportive of Theresa May, he clearly expects his son will walk into Number Ten in the not-too-distant future. “A man who’s been Brackenbury Scholar at Balliol can surely handle being PM.”

They seem close, in a reticent, upper-crust kind of way. Closer than he was to his parents, anyway. “I was packed off to boarding school at eight. My parents might reluctantly come down once a year to see me.”

He and Boris don’t speak that often – but then, as he says, they don’t have to. “If Boris wants to know what I’m doing he only has to switch on the TV. If I want to know what he’s up to I just pick up the papers.”

It doesn’t always work that way. He was possibly the last person to hear that Boris had resigned as Foreign Secretary. “I was in the Himalayas looking for snow leopards” – naturally, the way you do – “and didn’t find out until six days later when I got into Bishkek, the capital of Kyrgyzstan, you know.”

He thinks it was the right decision. “He couldn’t do anything else after saying that trying to sell the Chequers deal was like polishing a turd, and talk of Britain being a vassal state is fairly apt. Curiously, I had spent that week in pursuit of snow-leopard turds. Funny, that.”

He doesn’t think Boris has necessarily blown his career. “It’s a mess. Anyone who came forward and said they would deliver a real Brexit would stand a very good chance of being heard in the country as a whole. Stop faffing. We are leaving. Full stop.”

You can’t help feeling part of what drives Stanley in his late-septuagenarian frenzy for fame is to be known as more than “Boris’s dad”. When I ask him about his motivation, he comes up with some guff about how being well known helps his environmental campaigning, but quickly realises he’s sounding like a Miss World contestant. “I’ve written 25 books but there are no points for that these days. I walk down the street and people say, ‘Oh, hello, Stanley.’ Maybe it’s vanity, but it’s the most cheering thing.”

His children [six in total] are “totally supportive and not in the least embarrassed” about his late-flowering television career. His wife, Jennifer (his second), rather less so. He didn’t ask her advice about doing I’m a Celebrity – “She’s very sniffy about the whole thing; she’d only have said, ‘On no account do it’.”

Instead, he set off on a previously planned trip, telling her that if he didn’t come back she should look in her drawers – “No, not those kind of drawers” – for a clue… a note, apparently, that just said, “Put the television on”.

Predictably, he “had a marvellous time – loved sitting around, and the trials were no worse than prep school.” He developed a “deep and meaningful relationship” with a dishy young blonde called Georgia Toffolo, known in the shallower reaches of television by the sobriquet Toff, who went on to win the series. How the producers must have hugged themselves.

“Sweet girl. Went to Blundells. Not in the first rank of public schools, of course.” (Stanley went to Sherborne; Boris, famously, to Eton.) “Unbelievably, she turns out to be a supporter of the Conservative Party.”

There’s a lesson here for Theresa May – and, perhaps, Boris – he thinks. “This reality TV stuff we were doing plays so well with the younger generation, and if the Tories need anything, it’s to attract the younger generation.”

I had two thoughts as Stanley cast his diet aside and we ordered our first bottle of the Garrick Club claret. First, that perhaps the saviour of the Conservative Party might turn out to be Johnson senior, not Boris, after all. Second, how come in the jungle he got to pair up with the glamorous Toff and I ended up bonding with Edwina Currie? Fine woman, of course, but still… Life can seem unfair, sometimes.

The Real Marigold Hotel first starts on Wednesday 1st August at 9:00pm on BBC1