“We feel that nuclear is an important part of the mix. But we’re more nimble, I would suggest, than the French, because we have a diverse source of energy supply. They’re essentially betting the farm on nuclear. That’s their main instrument. We have a range of things. You need to have a diversity of supply because that gives you a measure of security as well, because you’re not just relying on the gas price, you’re not just relying on your nuclear fleet working.”

Currently, the Government is only committed to financing one new large-scale nuclear plant by the next election. Some MPs are pushing for the equivalent of eight large plants by 2050. What level of ambition can we now expect to see from the Government?

“With energy, you’re thinking maybe 30, even 40 years [ahead]. If we fast forward to 2050, there is a world where we have six or seven sites in the UK. That isn’t going to happen in the next two years. But it’s definitely something that we can aspire to.

“The Prime Minister said, in terms of the energy generation mix, we could see maybe a quarter of that being nuclear, I’d say 15 to 25 per cent … But obviously, you’re not going to suddenly have six new nuclear stations in the first three years. I mean, it’s physically impossible to do that.”

Kwarteng confirms that ministers have agreed to set up a new body to oversee the delivery of the new plants. Asked what arguments he has used to lobby Sunak for vast sums of money at a time when the Chancellor is resisting further public spending, he says: “I think it’s a long term thing. And also, we’re committed to having a vehicle which looks at this, and which actually can facilitate that, and I think there’s a measure of agreement on that. Obviously I don’t want to anticipate what’s in the strategy.

“But I think there is a realisation across government that we could do more on nuclear, and that’s why in the Prime Minister’s 10 Point Plan, which was published in November 2020, the third point was all about nuclear.”

He adds that small, modular reactors (SMRs) could be placed together on individual sites to create the equivalent output of large reactors.

“There’s the large scale nuclear, which we know about, and the SMRs, which the Prime Minister has talked about. Essentially it’s almost like a battery of smaller reactors. So Hinkley has got two reactors, and they are 3.2 gigawatts. These smaller reactors, you could see maybe 10 on the site, where they are each maybe 300 megawatts. That’s the idea.”

Kwarteng has a reputation for self-confidence and plain speaking that appears to go back some time.

Aged 18, the then Eton scholar is said to have reassured a relatively young tutor at Trinity College, Cambridge, who mentioned that this was his first time interviewing entrance candidates. “Oh don’t worry, sir, you did fine,” Kwarteng is said to have told the tutor.

Two years later, he appeared on the pages of The Sun when, representing Trinity on University Challenge, he was heard to mutter “oh f—, I’ve forgotten”, having buzzed in to answer a question.

His plain speaking has, on occasion, created friction with fellow ministers. His suggestion in a television interview last year that the business department was in talks with the Treasury over a support package for collapsing energy firms sparked a major public row, when a Treasury source retorted: “This is not the first time the [Business] Secretary has made things up in interviews. To be crystal clear, the Treasury is not involved in any talks.”

Now, Kwarteng rebuffs a remark by Oliver Dowden, the Conservative Party chairman and a Cabinet colleague, who warned in a speech that British people “want to see a bit of conservative pragmatism, not net zero dogma”, given the current crises.

“I hate dogma. Ask anyone who works with me … There’s no dogma, we don’t do dogma,” Kwarteng says.

“I think we could do two things. I think we can get off Britain’s reliance on fossil fuels – decarbonise is the technical word – and have more energy security and greater affordability. We’re a highly innovative country.”

He also has no time for Sir Keir Starmer’s apparent struggles to define a woman, in the context of debates over trans rights. “Everyone knows their mother. Their mother is a woman. They know what that is, intuitively, it’s common sense. So this idea that politicians are literally tripping over words is, I think, pathetic.

“If someone can’t say, ‘my mother is a woman’, would I trust that person to run the country? With Keir I think he’s just trying to keep a very vocal and radicalised wing of his party on side. And so he can’t really say boo to a goose. He can’t even tell you what day it is because people will be cross. He’s juggling this crazy coalition. Let’s see how he does.”

On closer inspection, when leaving Kwarteng’s office, it transpires that a paper cut-out of a small Julie Andrews figure has been mischievously stuck to the turbines mural, as a re-imagined scene from The Sound of Music. A picture of Kwarteng’s face has been stuck over that of the Andrews figure.

Although a strategy document can easily be written at the eleventh hour, presumably to replace the turbines with a nuclear power plant would have presented more of a challenge.