(FILES) This file photo taken on February 22, 2016 shows Mayor of London Boris Johnson as he leaves his home in London. The plot was hatched over a slow-roasted shoulder of lamb: two Conservative heavyweights decided to defy Prime Minister David Cameron over Europe, igniting a feud that is creating a bitter rift in the party. The setting was the north London home of the city's charismatic mayor Boris Johnson -- one of the schemers and a longtime rival of Cameron's with ambitions to replace him in Downing Street one day. / AFP / CHRIS RATCLIFFE (FILES) This file photo taken on February 22, 2016 shows Mayor of London Boris Johnson as he leaves his home in London. The plot was hatched over a slow-roasted shoulder of lamb: two Conservative heavyweights decided to defy Prime Minister David Cameron over Europe, igniting a feud that is creating a bitter rift in the party. The setting was the north London home of the city's charismatic mayor Boris Johnson -- one of the schemers and a longtime rival of Cameron's with ambitions to replace him in Downing Street one day. / AFP / CHRIS RATCLIFFE

LONDON: The plot was hatched over a slow-roasted shoulder of lamb: two Conservative heavyweights decided to defy Prime Minister David Cameron over Europe, igniting a feud that is creating a bitter rift in the party. The setting was the north London home of the city's charismatic mayor Boris Johnson - one of the schemers and a longtime rival of Cameron's with ambitions to replace him in Downing Street one day.

The other man was justice minister Michael Gove, an intellectual leading light of the Conservative party and friend of the prime minister who has harbored resentment against him over a high-profile demotion. Gove's wife Sarah Vine, a columnist for the Daily Mail, described the evening as "all a bit surreal", with the two MPs sitting side by side on a sofa in Johnson's "stylishly dishevelled drawing room".

It was a couple of days before Cameron went to Brussels last month for a European Union summit that has paved the way for an in-out membership referendum on June 23 that has divided Cameron's Conservatives. In the tight-knit world of Westminster and especially in Cameron's inner circle - where many members attended the same university, Oxford - old rivalries and personal grievances are coming to the fore.

"This is a high-risk, high stakes game from which there will be no going back, either for the prime minister or for his Tory opponents," Daily Telegraph columnist Allister Heath wrote this week. After Cameron returned from the summit and announced a date for the referendum, Gove and five other cabinet ministers broke with the prime minister's pro-EU line and joined the ranks of Brexit backers. They were quickly joined by a third of the party's MPs including Johnson, who went to Eton College with Cameron and was a member of the same exclusive dinner club when the two were at Oxford University.

'Spin, Smears and Threats'

For an older generation of Conservatives, opposition to Europe is more an article of faith than a matter of policy - an explanation for the level of rancor. The reasoned arguments laid out in Gove's letter explaining his position quickly turned into name-calling and barbed comments from others, with parliamentary sketch writers picking up on a poisonous mood between Conservative cliques in the House of Commons. Welfare minister Iain Duncan Smith, one of the six rebels, wrote in the Daily Mail yesterday condemning "spin, smears and threats" from the pro-EU camp. "The acrimonious manner in which all this has been conducted is troubling and will I fear have consequences long beyond June 23," he said.

Foreign minister Philip Hammond has reportedly called leading eurosceptic Bill Cash a "total shit", while Johnson dismissed as "baloney" Cameron's attempt to make a positive case for staying in Europe.

Tim Bale, politics professor at Queen Mary, University of London, warned there was a risk that "a cumulative drip drip of a thousand petty cuts could turn a difficult situation into a crisis". In a fiery speech last week, Cameron launched a thinly-veiled and scathing attack on his old rival Johnson, dismissing his ideas as "for the birds" and mocking his barely concealed political ambition. Johnson hit back with an article in The Sun, Britain's most popular newspaper, in which he mocked Cameron for "clutching the skirts of Brussels".

'All Guns Blazing'

"Both sides are trying to find their range at the moment. They're not engaging in close combat yet," James Forsyth, political editor at the Spectator magazine, which Johnson used to edit, told AFP. But Forsyth said the internecine conflict so far "is not anywhere near as vicious" as the 1990s when Conservative ministers openly feuded over whether Britain should adopt the Maastricht Treaty. That conflict ultimately led to the downfall of then Conservative prime minister John Major, a staunch pro-European.

The sparring over the referendum is important for Cameron's future too as he has committed to leaving office by the time of the next election in 2020 without saying when or who will replace him. Forsyth said Cameron faced a choice between a measured campaign that would allow him to unite the party afterwards or going in "all guns blazing". "I think he's temperamentally more inclined to the latter," he said, adding that the prime minister "isn't pulling his punches at the moment". - AFP