Scottish independence exclusive: Rebel MPs plot instant revolt against Cameron, if Yes campaign win

David Cameron could face a leadership challenge from his own backbenches if Scotland votes in favour of independence, as Tory rebels blame him for presiding over the break-up of the Union.

The Independent understands that discussions have already taken place among Tory MPs considering standing a candidate against the Prime Minister if the Yes campaign is triumphant on 18 September.

Recent polls suggest the referendum vote is on a knife edge, with the nationalists eating into the Better Together campaign’s long-term lead.

Mr Cameron yesterday insisted he would not resign if Scotland voted to leave the United Kingdom, but some disaffected backbenchers claim that his position – as the PM who lost Scotland – would be “untenable”.

“The move will take place immediately,” said one senior Tory MP. “David Cameron will be unable to contain the anger at the humiliation. His position will be terminal.”

A former government minister said: “Losing Scotland would be a traumatic event, a horror show that David Cameron could not possibly survive.”

While many Tory troublemakers may choose to keep their powder dry until after the 2015 election, some of those sounded out by The Independent are preparing for an instant challenge to Mr Cameron’s authority.

Backbench unrest over the UK’s relationship with the EU means the Scotland issue will be combined with other anti-Cameron grievances. One MP expected to be the leading figure in the revolt if the PM tried to stay on after a Yes win, said: “This isn’t a coup d’état, or a sinister plot. It would be the consequences of a catastrophe. There would be a flood of anger.”

As the referendum polls narrow, Mr Cameron’s early handling of the referendum negotiations with Scotland’s First Minister, Alex Salmond, and his decision to effectively take a back seat in the process, are being heavily criticised.

Last month the former Tory leadership contender, David Davis, said David Cameron would have to consider stepping down if there was a Yes result. Mr Davis, who stood against Mr Cameron in the 2005 leadership contest, said the Prime Minister would be left “humiliated” if the union ended on his watch. However, he said it would be the PM’s “call” to either choose to go or stay in 10 Downing Street.

Though there has been simmering disquiet in Tory ranks over Mr Cameron’s strategy in effectively farming out defence of the union to the BetterTogether campaign led by the former Chancellor, Alistair Darling, some now believe this tactic denied any positive pro-union message from Westminster the authority of government.

“There has been widespread complacency and a lack of historical perspective,” said another leading backbencher, who added: “We’ve asked for Scotland to stay but failed to shout loud enough. There is every chance that David Cameron will take his place in history alongside Lord North, who presided over the loss of the American colonies in the late 18th century.”

The poor performance of Mr Darling in the second televised debate with Mr Salmond, the boost this gave the Yes campaign, and the revamped strategy of the nationalists to concentrate on the fear factor of Tory-led governments in Westminster weakening public services – including the NHS – with further privatisation, have all contributed to the polls narrowing.