Deadly robots that can climb trees, AI friends and a work-less future were among the topics as Rishi Sunak sat down with Elon Musk.

The prime minister held a highly unusual "in conversation" event with the billionaire X and Tesla owner at the end of this week's summit on artificial intelligence.

Throughout the wide-ranging and chummy discussion, Mr Musk held court as the prime minister asked most of the questions.

The pair talked about how London was a leading hub for the AI industry and how the technology could transform learning.

But the chat took some darker turns too, with Mr Sunak recognising the "anxiety" people have about jobs being replaced, and the pair agreeing on the need for a "referee" to keep an eye on the super-computers of the future.

Tech investor and inventor Mr Musk has put money into AI firms and has employed the technology in his driverless Tesla cars – but he's also on the record about his fears it could threaten society and human existence itself.

"There is a safety concern, especially with humanoid robots – at least a car can't chase you into a building or up a tree," he told the audience.

Mr Sunak – who is keen to see investment in the UK's growing tech industry – replied: "You're not selling this."

It's not every day you see the prime minister of a country interviewing a businessman like this, but Mr Sunak seemed happy to play host to his famous guest.

And if he seemed like he was enjoying it, it should be no surprise – he previously lived in California, home to Silicon Valley, and his love of all things tech is well-documented.

In a hall that size, Mr Musk was difficult to hear and mumbled through his elaborate musings about the future, but refrained from any off-the-cuff remarks that might have caused Downing Street embarrassment.

The event was held in front of invited guests from the tech industry in a lavish hall in central London's Lancaster House.

Unusually for an event involving the prime minister, TV cameras were not allowed inside, with Downing Street instead releasing their own footage.

Some reporters were allowed to observe – but told they could not ask questions.

The pair discussed the potential benefits of AI, with Mr Musk saying: "One of my sons has trouble making friends and an AI friend would be great for him."

There was also agreement on the possibilities AI presents for young people's learning, with Mr Musk saying it could be "the best and most patient tutor".

But there was a stark warning on the potentially ruinous impact it could have on traditional jobs.

"We are seeing the most destructive force in history here," Mr Musk said, before speculating: "There will come a point where no job is needed – you can have a job if you want one for personal satisfaction but AI will do everything.

"It's both good and bad – one of the challenges in the future will be how do we find meaning in life."

Amid all the philosophising, there was little in the way of new announcements about how the technology will be employed and regulated in the UK – aside from the prime minister's promise that AI could be used to improve the government's own website.

Mr Musk was one of the star guests at this week's summit – but it briefly looked like the event with Mr Sunak might be a little overshadowed.

Hours before it was due to begin, Mr Musk took to his own website X, formerly known as Twitter, to take a swipe at the summit.

As Mr Sunak was on his feet giving his final press conference at Bletchley Park, Mr Musk shared a cartoon parodying an "AI Safety Summit".

It depicted caricatures representing the UK, European Union, China and the US with speech bubbles reading "We declare that AI posses a potentially catastrophic risk to humankind" – while their thought bubbles read "And I can not wait to develop it".

But in the end, the pair appeared at ease together, and Mr Sunak in particular looked in his element – perhaps even slightly bowled over by the controversial billionaire, who he called a "brilliant innovator and technologist".

From the cheap seats behind the dignitaries of the tech world, it was hard to put your finger on who was really the powerful one out of this pair.

Was it Mr Sunak as he asked the celeb tech billionaire questions? Or was it Mr Musk, who did much of the talking?

Either way, both men hope to have a say in whatever our AI future has in store for us.

Additional reporting by Tom Gerken