It is the Tory rutting season again.
In Manchester, the party's two alpha males will once again compete for the love of the faithful. David Cameron may be top stag but the doe-eyed adoration of the rank and file is more often reserved for Boris Johnson.
Conference is the Mayor of London's natural arena and he knows it. The Prime Minister may have the top job title but so often it is Johnson who has the party eating out of his hand. It crystallises the tensions in their relationship.
This annual joust between the two Eton and Oxford men – in which Johnson invests the same indecorous will to win as his sweat-drenched efforts at wiff-waff or tennis – began even before Cameron became leader in 2005. That year, it was Cameron who came out top. His leadership campaign had started badly, but his impressive note-free address to conference in Blackpool that October won him the day.
Whatever the outward appearances, Johnson's nose was out of joint. He drafted a subtly wounding Telegraph column that week that cleverly left the impression that Cameron should be seen as an over-praised unknown. Noting that he had "lost count" of the number of people who had asked him why he was not standing himself, Johnson contrasted this surprise with the "look of anxious blankness" when he told them he was backing Cameron instead.
He describes this look as one that "you see when people are sure that they ought to have read some classic work, and are in two minds whether to bluff it out or admit ignorance".
But when Cameron was duly voted in as leader in December 2005, he promoted Boris from the backbenches (where he had languished since being fired from the shadow arts job for lying about his affair with Petronella Wyatt). The higher education portfolio, however, was something of a pyrrhic victory. Johnson was forced to resign from the editorship of the Spectator – thus surrendering a handsome salary and stock-option package.
In public, Johnson maintained his usual act of cheery buffoonery. But in private he was fuming at the injustice of a man two years his junior becoming leader and omitting to give him a "proper" job. After all, Johnson had been one of the first MPs to back Cameron for the leadership and he had done so, in his own words, "out of pure, cynical self-interest". He expected greater pay-back than third fiddle on education.
Perhaps these feelings of resentment were in his mind when canvassing ideas from his staff one Wednesday afternoon for one of his Telegraph columns. As usual the search for inspiration led to a peculiar competition to suggest the theme most likely to derail Boris's career. Boris seized on one suggestion with such glee that he immediately sat down and began composing an introduction beginning: "One thing that has become apparent to me in my years of Parliamentary service is that David Cameron is a complete c**t." All good public-schoolboy fun of course, but his enthusiasm left few present that day unclear of Johnson's true thoughts.
At the next party conference in October 2006, Cameron's first as leader, Boris exacted his revenge. The Tory leader was due to deliver a crucial message about the NHS being "safe" in Tory hands and the media were keyed up to cover this pivotal moment in the party's march back to electoral acceptability.
Only instead of focusing on the leader's words, most political hacks were in hot pursuit of Johnson, who had attacked Jamie Oliver, the patron saint of healthier school dinners, only days after Cameron had praised him lavishly.
Cameron joked about the incident the next day but no-one believed he really considered it either funny or accidental – whatever Boris's protestations of innocence.
How Boris really thought he would benefit from stealing the attention away from his boss is unclear. His motive seems to be in part an explosion of envy, but tinged with a certain death wish. As one friend put it to me: "Boris is incapable of seeing a button marked 'self- destruct' without giving in to the urge to press it."
Within a month he appeared to be at it again when he laid out the case in his column – apparently in all seriousness – for giving the Iranians the nuclear bomb.
So incensed were the leadership once again that Boris's team were given to understand that he had lost an imminent promotion to shadow Europe minister as a direct result. It all added to Boris's reputation as untrustworthy amongst the leadership (and even Cameron's wife, Samantha, who is said to be also deeply offended by his philandering).
Despairing of his Parliamentary career, in March 2007 Boris began talking to confidants about trying for Mayor of London as an "interesting" exit route that would also cash in on his undoubted box-office status. But Cameron was "pleasantly dismissive" of the idea, preferring to pursue a string of other big names who, however, for one reason or another, all faded away. The idea of a Johnson mayoralty was considered preposterous and dangerous.
In July, Cameron reshuffled his Shadow Cabinet, bringing in a number of MPs both younger and less experienced (such as Michael Gove) but again leaving out Johnson. A senior Cameroon explained: "There was a feeling of 'do we really need to promote Boris?'"
It was a seminal moment. His hopes dashed, Boris began sizing up the mayoralty in earnest. Although he insists it was his idea to run, at the time he went out of his way to make Cameron (now devoid of any other plausible candidate) sweat by playing hard to get. He knew that the leader, who had been so dismissive of him, was now the one in Boris's power. So concerned was Cameron that he texted him with the message: "Don't go wobbly on me now." "Boris really didn't want to do it," according to one well-placed Cameroon. "We – George Osborne, Dave himself, Andy Coulson, Steve Hilton – endlessly had to go on about the fact he could win. There were a lot of meetings and calls, and Dave would keep asking, 'Is he there yet?'"
Despite Johnson's valiant attempts to preserve his independence from Tory HQ, he was forced to cede overall control to Cameron's crack troops in the shape of Lynton Crosby and Lord Marland for the campaign. Cameron won that battle and Johnson won the 2008 mayoral election.
Boris might finally have secured a "big beast" political job, but he was bound to be overshadowed by the Prime Minister-in-waiting as the general election approached.
By 2009 Cameron, as Leader of the Opposition, was dominating the airwaves as the polls put him on track to be the youngest occupant of No 10 since Lord Liverpool. But not for long.
Conference, also in Manchester that year, gave Johnson his opportunity to seize the headlines again. Without even warning his closest staff, Johnson triggered another media frenzy with incendiary calls for a referendum on the Lisbon Treaty.
Like a middle-aged William Brown found near a broken window, Johnson once again professed innocence, but the Cameroons were fuming. Nick Boles, who had done so much to help Boris win City Hall, even sent Johnson a Mafia-style text stating: "Revenge is a dish best eaten cold."
No matter – when Boris took to the conference stage to the EastEnders' theme tune, it was clear who was the party darling. He continued to upstage Cameron at the odd joint appearance during the 2010 election campaign – including larking around on a visit to the Chelsea Pensioners.
But there was no mistaking his loss of position as most powerful Conservative when Cameron finally entered No 10, albeit in coalition with the Liberal Democrats. The less charismatic "stag" was now forming a national government; Johnson, said to believe himself the cleverest man in the world, was still judging "busker of the year" competitions. It was not an arrangement designed to give either party a smooth ride. Particularly as Johnson could be forgiven for surmising that a Tory party under his leadership might have achieved power without Lib Dem props.
Since then, of course, the fixed smiles have continued. Johnson makes great play at City Hall of exclaiming to colleagues: "Wait! I must text Dave about this!" In fact, a great deal of texting goes on, particularly after another of what Downing Street sources call "Boris grenades". And yet Cameron must appear to be unconcerned, putting out the message that "contrary to popular perception, the Prime Minister is not obsessed with Boris". He knows who is the more popular both within his party and outside it.
Johnson, meanwhile, instinctively knows when and how to cause trouble. His comparison of Coalition housing benefit reform to Kosovan ethnic cleansing was exquisitely worded and timed to catch the attention and support of Labour voters. (No matter that he later backpedalled in more pedestrian language; the point was made.) His denouncement of Coalition police cuts a day after criticism of his handling of this summer's riots fulfilled the same purpose in naturally left-leaning London. Meanwhile Team Cameron must grin and bear it. "It's part of his job to be distinct; it's no use if mayors are automatons," sighs one very senior Downing Street source.
The leadership cannot afford for Boris to fail in next year's mayoral elections – they are after all the Conservatives' first major electoral test since taking office. For that reason, Cameron and Osborne went along with the charade when Boris made great play of campaigning to save Crossrail during the spending review. He had long since been told it was already safe.
Johnson did well out of the negotiations – not because Cameron is his friend but most of all because he wants to see Johnson boxed in as mayor for another four years. To ensure his victory next year, a Downing Street source explains: "Boris is always treated as a very privileged person."
Although his invisibility during the campaign against the introduction of AV prompted yet more mutterings about Johnson's lack of team spirit, the sense of Johnsonian "untouchability" has remained. That does not stop tensions between the two men's offices, however. Sources within Cameron's note that media reports about the rivalry have "amplified" any real-life distrust and there have been occasions when papers and information have been held back.
As conference kicks off in earnest, so will the latest round in the Boris vs Dave tussle for supremacy. Just occasionally, the testosterone spills over into something rather more physical.
In private, Cameron likes to tell the extraordinary story of how Boris launched himself over a Downing Street table during one meeting in a bid to grab the Prime Minister's briefing papers. Cameron would not let them go and two of the most powerful men in British politics briefly grappled in an undignified tug of war. He's not saying who won.
Sonia Purnell is the author of 'Just Boris', published by Aurum Press Ltd (£20). To order a copy for the special price of £16.50 (free P&P) call Independent Books Direct on 08430 600 030, or visit www.independentbooksdirect.co.uk