A black truck with blacked-out windows rumbled over a concrete overpass and pulled up into an empty parking lot. With a hiss, the truck’s hydraulic doors slid opened. And out stepped a young, ruddy-faced Englishman, in a grey suit, red spotty tie and shiny shoes.

David Cameron, the leader of Her Majesty’s Opposition, was, as the local residents might say, in Da House. Moments later he was introduced by an anxious charity worker to a room of heavily tattooed Hispanic and black Americans. “This is David,” she said. “And he’s from England.”

David from England (“I’m here to understand a bit about what goes on here,”) was in a buoyant mood. The previous day he had spent the afternoon playing Robin to Arnold Schwarzenegger’s Batman in the governor’s cigar tent (erected outside his Sacramento office), where they discussed green politics and America’s system of elected mayors and elected police commissioners, which Mr Cameron hopes to emulate in Britain.

Mr Cameron would also like to emulate the personal touch of California’s Governor. “Look at me and think of Schwarzenegger,” he declared at one point during the visit.

Arnie presented Mr Cameron with his 12 favourite DVDs, including High Noon, The Godfather and Lawrence of Arabia. “They’re all at the top of my list, too,” said Cameron.

Although Mr Cameron’s stateside visit was billed as a fact-finding mission, it was also perhaps intended as reassurance that the Conservative Party’s loyalties still lie across the Atlantic. “The special relationship is part of the Conservative Party’s DNA,” he said.

“The problem that Blair always had was that his party didn’t feel the way that he did,” Mr Cameron told The Times. “But we should be the best friends [with America] rather than the newest friends. Clearly we’re the junior partner. But a best friend tells you what you need to hear, not what you want to hear.”

In East LA, Mr Cameron was visiting the Puente Learning Centre, a non-profit organisation that rehabilitates 2,000 students every year, with minimal funding or oversight from the government. He met Deseiriee Anderson, 27, from South Los Angeles, whose brother is serving a 25 year-to-life sentence for a gang crime. “I’m here to learn computer skills,” she said, as the Opposition leader sat on the edge of her desk, “and to get my gang tattoos removed.”

Before going to the Puente Learning Centre, Mr Cameron met David Doan, Commanding Officer of the Los Angeles Police Department’s Detective Bureau.

“Police reform in the UK is very important,” he said later, on his blacked-out tour bus. “What’s happening in the US is very interesting. Here you have elected mayors and elected police officials, and it works well.”

Not all of Mr Cameron’s visit to LA was spent touring the mean streets of Boyle Heights. He spent his first night at the Mondrian Hotel, the celebrity nightspot where Britney Spears was recently observed in less than happy circumstances. Amid the Lamborghinis, the parking valets and the poolside revelry of the Sky Bar (with its provocatively dressed waitresses), Mr Cameron must have cut a rather unlikely figure. Then again, he appears to have found new appreciation for popular culture. “I was watching telly in bed the other night and I started to watch a Channel 5 documentary on Britney, and it was captivating,” he said.

Mr Cameron himself has become something of a cult figure in the US, thanks to the broadcasting of Prime Minister’s Question Time on the C-Span channel. His fans include at least one US Senator, who Tivos it weekly.

Mr Cameron seems to think his sparring with his former rival made for better TV than his clashes with Gordon Brown. “Blair had an extraordinary mastery of the Commons,” he said, before adding, defensively: “I like to think that I did pretty well against him. I like to think that I lost as many as I won. And you wouldn’t believe the things they shout at you.”

Would President Bush fare well, if he was given the same treatment? Cameron almost answered the question, then seemed to remember to whom he was talking.

“I don’t know,” he said, quietly.

— The Government looks set to continue its raid on Tory policies, with a Cabinet minister suggesting last night that married couples may soon enjoy tax benefits under Labour (Hannah Fletcher writes).

Andy Burnham, the Chief Secretary to the Treasury, said: “I think marriage is best for kids. It’s not wrong that the tax system should recognise commitment and marriage.” Tax incentives for married couples have been much criticised by Labour ministers, who believe that it would discriminate against children with separated parents.

George Osborne, the Shadow Chancellor, said: “For two years David Cameron has been making the case for recognising marriage in the tax system and Gordon Brown has attacked him. Now one of his minions seems to say we are right.”

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