Sit back and enjoy the ride. Here was Boris Johnson in his comfort zone. A conference room at the Science Museum where he could indulge his fantasy as the Bertie Booster of British politics by giving his standard upbeat, cut out and keep after dinner speech – never mind that it was actually shortly after breakfast – to an invited audience of some of the world’s richest men and women at a Global Investment Summit.

This was Boris at his most optimistic. No need to mention the inconvenient truths of food and lorry driver shortages. Covid infection rates increasing at an alarming rate could also be safely ignored. Those were all just present day irritants. The story he wanted to tell was of a future in which Britain would lead the world to the promised land of net zero by 2050. A speech that was light on detail but peppered with recycled gags. Not that Boris got many laughs. Perhaps billionaires don’t have the same sense of humour as the rest of us. Or maybe they’d heard them all before at Davos.

Dominic Cummings has described the prime minister as an out of control shopping trolley veering from side to side down the aisles, and Johnson’s 15-minute cameo had all the hallmarks of someone playing Supermarket Sweep. Boris began by reminding everyone of the inventions that failed before attributing the success of the Covid vaccine to free market capitalism. Some might remember government funding and the NHS also playing a part. He then skipped to a passage where Brexit was creating new opportunities for investment – that will have come as a surprise to many of the business leaders who have relocated outside the UK – and invited everyone to join Britain in the green revolution.

“Green is Good,” he said, channelling his inner Wall Street, as he urged the Gordon Gekkos in the room to take advantage of the opportunities within the UK created by the need for a technological revolution. We were the country of Peppa Pig who taught Americans the right way to say tomato, petrol and mother. We were the country of Adele, Coldplay and Ed Sheeran. And the audience was just gullible hucksters out of Trading Places who could be conned into buying into Britain. Thank you and good night. Or rather, good morning.

Just as the audience was trying to work out whether it had been charmed or insulted, Boris returned on stage with Bill Gates to be interviewed by Allegra Stratton. This was a collector’s item as it was just about the first sighting of Stratton since she had been appointed to be the prime minister’s spokeswoman on the proviso that she never actually said anything or was ever seen in public. Stratton has now been reassigned as Cop26 spokesperson but she was first introduced as “a journalist” and she immediately went for the killer question.

“I believe you have an announcement to make,” she said. “I do,” Johnson replied enthusiastically. He had signed a deal with Breakthrough Energy, a Bill Gates company, worth GBP400m – half each from the UK government and the Microsoft founder – to develop solutions to the really tricky problems of global heating, such as green aviation fuel and green cement, that everyone else was shying away from as they were unlikely to turn a profit any time soon.

Gates interrupted. Actually the deal was worth twice what Boris had said. Johnson looked flustered. If he had signed up to double the amount he could be in deep shit with Rishi. Most would have put money on it being Boris who had got the figures wrong, but his spokesman later assured everyone that GBP200m was the government limit. It turns out that even a stopped clock can be right twice a day. In any case it was all loose change to Gates. He’d probably spent more on his daughter’s wedding than on the new green deal with the UK.

Stratton tried to steer the conversation back on track by saying that the prime minister had always cared passionately about the climate crisis. When he had made comments, such as windfarms not being able to blow the skin off a rice pudding, he had just been having a laugh. Deep down he had always been a believer. Except the only thing he really believed in was his own narcissism. His own exceptionalism. The normal rules of public engagement did not apply to him.

The longer the chat went on, the more Boris started to wing it. As if he was a public entertainer who was obliged to make up for the fact that Gates was a personality free zone who could be relied on to put any audience to sleep. So Johnson then said that Cop26 was going to be a huge success because everyone would be there – except possibly the leaders of China and Russia, two of the world’s largest polluters, without whose cooperation global action on the climate crisis is just pissing in the wind.

Boris also went on to say there were huge profits to be made from investing in long-term solutions to the climate emergency. Gates looked at Johnson in amazement. He hadn’t realised he had just signed a deal with a serial lunatic. Hadn’t he already said the whole point about these speculative technologies was that some would fail and that there might not be bumper returns? Or any returns? Certainly not in the foreseeable future.

Just to make sure everyone got the point, Gates repeated his caveat. Boris ignored him. He was in his bubble. He was the centre of attention. People with access to $24tn were his captive audience. And he was funnier than all of them. That’s what really counted. All was well with the world.