Boris Johnson has told David Cameron to expect a series of bust-ups over the next year as he seeks to differentiate himself from the national Tory party in his push to seek a second term as London mayor.
A series of recent interventions, which saw Johnson criticise a "lily-livered" failure by the government to toughen up strike laws and warn that housing benefit cuts could lead to Kosovo-style social cleansing, are being described as a warm-up for the mayor's re-election campaign.
One ally said Johnson's more cosmopolitan brand of Conservatism had proved more successful in London than the national party's more narrow offering in last year's general election.
"The Conservative party did not win London at the general election," the source said. "But Boris did win the mayoralty in 2008 because he is the sort of Conservative who can win in left of centre London – contemporary and cosmopolitan.
"The election next year will take place at a moment of maximum pain for the government as the cuts start to bite. It is hard at the best of times to win London as a conventional Conservative. We do not underestimate the challenge."
The rivalry between Cameron and Johnson, which dates back to their time at Eton and Oxford, was revived last week when the London mayor accused ministers of being "lily-livered" for failing to lift the threshold needed to call a strike. Johnson intervened after the RMT union called six days of strikes on the London Underground over two weeks. One cabinet minister said: "There was a bit of annoyance because of the delicate nature of relations with unions and the need to handle them with care." George Osborne was also less than pleased because he was planning to signal that the government is prepared to look at employment laws.
The spats between Johnson and 10 and 11 Downing Street raise the prospect of an ongoing battle over the next year as the mayor faces a strong challenge from Ken Livingstone in the mayoral contest. Downing Street and City Hall are making preparations for the inevitable, which will take place within the Queensberry Rules, according to one ally.
"Their relationship is not like Blair and Brown who came from fundamentally different backgrounds and were completely different characters. They both went to Eton and Oxford, though that does not mean they see the world in the same way."
The risk of increased tensions between City Hall and Downing Street comes as Tory MPs express growing admiration for Johnson, who was regarded as a political lightweight in his seven years as an MP until he resigned to take up the post of mayor in 2008.
Some MPs, who say he has become a serious politician, are hoping he will return to the Commons, where he would be a natural successor to Cameron. One ministerial source said: "Boris is hopefully lining up to become a true Conservative prime minister. He reaches out to Conservative audiences in a way David never really does. David is tolerated by the party because he has had some mild electoral successes. Boris will come back at Westminster if he loses next year. If he wins he will be in a strong position to come back either before or after the 2015 general election, saying he can reach out to parts of the country beyond the Tories."
Cabinet ministers accept that Johnson has a rare ability to appeal across the political spectrum in a way unmatched even by Cameron. One cabinet source says: "Boris will never be seen as a dull automaton controlled by the party centrally. He is seen as more Conservative than the coalition in the way he has criticised the 50p tax rate and public sector unions. But he is seen as to the left of the coalition in the way he has fought for investment in Crossrail and investment in areas across London."
Cameron is letting it be known to his allies that he is relaxed about Johnson, who has craved his job since he flirted with the SDP at Oxford to win election as president of the union. A bit of dissent is fine, goes the message, though a line will have to be drawn to prevent the Labour party and Johnson's mayoral challenger, Ken Livingstone, exploiting the differences.
Comparisons are being drawn with the future prime minister's reaction when Johson upstaged him at the Tory conference in 2006 by expressing support for mothers who defied Jamie Oliver's school food campaign, directly contradicting Cameron. "Just try not to do it all the time," Cameron said after declaring that it was fine to go off message.
Allies of Johnson are confident they can manage the inevitable tensions over the next year as Livingstone tries to depict the mayor as no different from the Etonian prime minister. "Boris deals directly with Dave and George," one source says. "They text each other all the time."
Relations have eased since the departure of Downing Street's director of communications, Andy Coulson.
While Johnson is keen to differentiate himself from Downing Street he knows it is in his interests not to go too far. One ally said: "For some bizarre reasons Ken Livingstone is claiming he will be able to get more out of this government than Boris. But Boris is no more than a text away from the prime minister and the chancellor."
Johnson's re-election campaign will stress how his links with No 10 and the Treasury have delivered results. He will point to the agreement on the funding for Crossrail and will say that Osborne agreed to delay by a year the introduction of controversial housing benefit changes. The mayor had warned the changes could prompt Kosovo-style social cleansing.
But the mayor will also be stressing his own achievements. He will say that one of his main themes of the 2008 campaign – cracking down on bus crime – has led to a reduction in attacks by one-third. He will say crime is down in the capital by 9%.
"Boris wants to fight the campaign on the practical improvements he has brought to London," a source said. "The challenge is to show you are making the most of the Olympics [which open two months after the election]. Boris's mission for the next year is to lead London out of the recession and prepare London for the Olympics."
Johnson is two years older than Cameron, which meant that at Eton Cameron watched the showman from a relative distance. At Oxford the future prime minister kept a distance from student politics, which meant that he was not close to Johnson, though they were in the Bullingdon Club at the same time.
One senior Tory explained the differences between the two men. One senior Tory says: "David and Boris are different. Boris's background is a bit more exotic. In David's case you could not get someone who is more English. They have a different temperament. They are natural rivals but there is no emnity. There is even some affection.
"With Boris there is this sheer ruthless animal energy. David is a much cooler customer."
The source turned to Romeo and Juliet, which opens with a brawl between supporters of two of Verona's great houses, to illustrate the point. "David and Boris have a different approach to life. But there is no Montague and Capulet blood enmity."
One senior Tory said that Cameron came to terms long ago with Johnson's ambition. "The whole Johnson family are ruthlessly ambitious. When Boris entered the House of Commons he did not think he would be mayor. He is now concentrating on his re-election. He will advance, advance and then find his next challenge. He could be prime minister, he could be UN secretary general, or a Nobel prize winning author or he could be foreign secretary. You just do not know."
It is not just the mayor who is ambitious. "People will always write about splits and rivalries about Boris because it is in the Johnson DNA. If it is not about David then it is about Boris's sister Rachel or his brother Jo. If you have a thoroughbred people will want to see it race against a champion."
The next year will prompt speculation about Johnson's future. One Tory says: "Of course Boris wants to be prime minister. Boris is like a child in the playground. He sees the ice cream and just goes for it even if another child is eating it."
But he believes the timing is against him. "If he wins next year he stays mayor for another four years until after the 2015 election – unless he stands down early. If he loses next year he will no doubt seek a seat in the Commons. The problem for him is that going back to the Commons will be seen as a hostile act."
One ally of Cameron believes the mayor will never become prime minister. "I really can't see Boris as prime minister, just as I can't see Ken Livingstone, Oona King, Steve Norris as prime minister. You get my drift.
"Boris is much more ambitious than David. He has always been scheming and working out his next move. But his ambition was always apparent. David has always had an easier manner. I'm not sure this country is ready for a philanderer as prime minister."
