The four plots to knife Cameron The dinner in a smart Westminster house in the shadow of the House of Lords brought together some of Margaret Thatcher's most devoted supporters. The mood of the Tory MPs in the No Turning Back group, set up to keep the Thatcherite flame burning, was bloody and fractious after the party trailed behind Ukip in the Eastleigh by-election. The discussions over tomato soup and smoked halibut two weeks ago were dominated by criticism of David Cameron's leadership. The diners shared the view of an increasing number of senior ministers that the Coalition is a mistake - and that David Cameron, far from being an asset, is the reason that the party's support slumped at the weekend to a new low of 27 points, with only seven per cent of Tory supporters believing they can win the election. Many blame Cameron for the slump in support the party has had of late, and plots against him are increasing Among the 25 MPs at the dinner were three former leadership contenders: David Davis, Liam Fox and John Redwood. The No Turning Back dinners are usually held on the basis of strict confidentiality. The gathering was billed as The Dinner Party Plot in a deliberate leak to the Press which was calculatedly designed to undermine Cameron. There were the usual grumbles from the MPs over the economy and Cameron's decision to press ahead with gay marriage in the face of massive opposition in his own party. But there was more profound criticism of his "lofty" leadership style and the airing of the idea that he is "too privileged" to connect with ordinary voters. Even his pledge for an in/out referendum on Europe after the next election - a move designed to appeal to the Tory Right - was shredded by Davis, Fox and Redwood, who want a referendum next year. Confident: Adam Afriyie Distrusted: David Davis As the wine flowed the mood turned uglier and at least three unnamed Tory MPs demanded Cameron's head before the election. The Justice Secretary Chris Grayling, who was guest speaker, was aghast and warned the MPs it would be "madness" to challenge the PM. But he convinced few people. "The fact people are willing to say Cameron has to go in the presence of a minister who will report back to No 10 tells you the mood of the party," says one MP who was there. Unflappable: Theresa May Ambitious: Boris Johnson Liam Fox went public with his criticisms in a speech on Monday at the Institute of Economic Affairs when he called for a radical rethink about the economy. Davis, who is deeply distrusted in Downing Street, is planning to return to the economic fray in a speech in the Commons. But it is not just in private dining clubs that the knives are out for Cameron. At least three other plots to replace him can now be identified. They involve Theresa May, the Home Secretary; Adam Afriyie, the Tories" first black MP; and the hugely ambitious Boris Johnson, who is now barely on speaking terms with either the PM or the Chancellor George Osborne. Liam Fox went public with his criticisms of the PM in a speech on Monday at the Institute of Economic Affairs when he called for a radical rethink about the economy Theresa May's position became clear at a ConservativeHome conference in Westminster on Saturday, which was optimistically titled: Victory for the Conservatives in 2015. The conference was attended by some of the Tories" biggest hitters - Lord Ashcroft, the former Treasurer who has stopped giving his millions to the party and questioned whether Cameron is a genuine Conservative, was on the speakers" platform. When Mrs May, 56, made the keynote speech, she was expected by her Cabinet colleagues to use it to dampen down speculation about her leadership ambitions. How wrong they were. It was a clear vision of what a May premiership would look like complete with an implicit rebuke for Cameron for standing by NHS chief Sir David Nicholson after the Mid-Staffordshire scandal. Is Theresa May attempting to forge links with Mr Gove, who insists he is not interested in running for the leadership? In the most radical section, she proposed businesses should be able to run new free schools at a profit, which is a key demand of Michael Gove, the Education Secretary. Is May attempting to forge links with Gove, who insists he is not interested in running for the leadership? If so, she may have misjudged him. Her overt leadership ambitions caused huge resentment. Gove, angered that he had been linked to May after her speech, lambasted the "disloyal" Home Secretary before the start of Cabinet this week. The Education Secretary said he had been "shocked" to see some ministers positioning themselves for a future leadership race. It was clear the Home Secretary was his target. Downing Street "sources" later described May as "grotesquely naive" and dropped dark hints that she was not doing the job as well as she thought she was. In the febrile atmosphere at Westminster, Philip Hammond, the Defence Secretary, has been suggested as her preferred choice for Chancellor. Although Hammond has denied the reports, it has been said they would run on a Top Gear ticket of "May and Hammond" - named after the presenters of the BBC show James May and Richard Hammond. It is a measure of just how febrile the Tory Party is that as recently as 12 months ago most MPs would have scoffed at the notion of May becoming leader. Derided as being a "charisma-free zone," May's most interesting characteristic back then was considered her predilection for kitten heel shoes. But she has proved a great success at the Home Office - traditionally a political graveyard - with crime and immigration falling. While publicly fiercely loyal to the PM, the Home Secretary believes she can become the party's second woman leader after Margaret Thatcher. With the latest poll showing the Tories trailing Labour by 12 points among female voters, the ousted Cabinet Ministers Cheryl Gillan and Caroline Spelman are working behind the scenes to support her. At the weekend, Maria Miller, the Culture Secretary, who is one of the most senior women in the Cabinet, jumped on the May bandwagon saying she "has fantastic credentials for the job." Suspicions that the women are running a concerted campaign was heightened by the trenchant intervention of Sarah Wollaston, a GP and new intake MP, who said Cameron is "running out of time" to rid the party of the "posh, male, white" image. May gave an implicit rebuke for Cameron for standing by NHS chief Sir David Nicholson after the Mid-Staffordshire scandal Theresa May could not be more different from the central character in the second plot. Multi-millionaire Tory MP Adam Afriyie, dubbed the "Tory Barack Obama," was the first to be outed as building a leadership team in the event of a backbench revolt forcing the Prime Minister to resign. The widespread derision that has greeted the disclosure of the campaign by Afriyie, 47, who struggled to rise beyond the position of shadow science minister before the election, has done nothing to puncture his confidence. The clever backbench Tory MP Mark Field, denied ministerial office by Cameron - who can't stand him - is masterminding the Afriyie operation. Some of those campaigning for Afriyie want to remove Cameron immediately on the grounds he failed to win the last election against the hugely unpopular Gordon Brown and is therefore certain to lose the next. Others, notably Afriyie himself, want a credible candidate in place in 2015 if Cameron is beaten. More from Andrew Pierce... Under Tory rules, a vote of confidence in Cameron would be triggered automatically if 15 per cent of the parliamentary party - 46 Tory MPs - write to Graham Brady, the chairman of the 1922 Committee. Afriyie campaign members are working hard to secure letters of support. Of all the threats to Cameron, however, potentially the most serious comes from Boris Johnson, 48, the London Mayor. Earlier this week, at a business conference in Cannes, France, Johnson was asked if he could ever attempt to become Prime Minister. He said, as he always does, that he was "very, very happy" being Mayor of London. But he also said: "After 2016 [when his four-year term ends] who knows what will happen." His supporters are hoping something might happen before that and are casting meaningful glances towards Croydon South, where the retiring Tory MP Richard Ottoway has a thumping 16,000 majority. Johnson has been suggested as a replacement for Ottoway at the next election so he can run for leader if the Tories lose. But some of his supporters, who include former minister Lord Marland, have a more radical plan. They want to persuade someone like Ottoway to stand down sooner if the poll ratings deteriorate. A seat in the Lords would be dangled in front of Ottoway as an incentive to go. Even if Ottoway agrees to the plan, it is fraught with difficulties. For a start, the seat is not his to gift to Johnson, or anyone else, because Conservative associations jealously guard their independence. On the other hand, relations between the leadership and the voluntary party have never been so bad and Johnson is hugely popular - so the local association might jump at the chance of securing him as their MP. One Johnson backer says: "Boris is the most popular politician in the country. We need him back in the Commons. It is Theresa May who has emerged as the most plausible "Stop Boris" candidate because of her surefootedness at the Home Office. In fact, May is the first Home Secretary since Labour's Roy Jenkins in the Sixties whose stature has grown rather than shrunk in the Home Office. It is not just on crime and immigration that she is making progress - she has also won plaudits for challenging the notoriously militant Police Federation over pay and perks, a move that even Margaret Thatcher baulked at. And last year she defied the White House and refused the American extradition request for the Asperger's sufferer Gary McKinnon, who hacked into U.S. military computers. Another woman Tory MP said: "By choosing Theresa we would make Labour and the Liberals look so behind the times. Theresa is not the next Maggie Thatcher. She's sensible, unflappable, much more like Germany's Angela Merkel. And Merkel, after Lady Thatcher, is the second most successful woman politician in Europe - a fact which has been noted by more and more of Theresa May's admirers.