A TORY scare tactic claiming Labour would form a pact with "wicked Scottish nationalists" helped win them power and they will use it at every future General Election to frighten English voters.

Former Labour minister Chris Mullin maintains the shock outright Tory win in 2015 was largely due to the false claim that the party would ally with the SNP to form a government.

He told the Sunday Herald, "the Tories discovered in the last election – that halfway through the last election campaign that if you got your phone bank to ring around people in marginal constituencies saying 'you don't want a Labour government propped up by those wicked Scottish nationalists do you?' it had a remarkable effect on English voters who ran a mile.

"It was one of the reasons in the last two weeks of the election campaign that there was an unexpected swing to the Tories that gave them an overall majority that no one anticipated.

"And Tories have told me this, it was because of the impact of that change of tactics half way through the campaign and no doubt that will be a feature of all English election campaigns for the foreseeable future," he added.

He suggested the Tories would use English nationalism and perceived hostility south of the border to the SNP in an attempt to derail Jeremy Corbyn's campaign at the next General Election.

The former MP who served as a minister under Tony Blair also wrote the acclaimed novel, A Very British Coup, about the election of a left-wing Labour government facing attempts by the secret services and the US to topple it from power.

Mullin, who was a close ally of the late Tony Benn and also played a leading role in the acquittal of the Birmingham Six, said there were policy areas where the SNP and Labour had "a lot in common".

However, he said he opposed formal a pact between the two parties because he feared it could assist the Tories in promoting scare stories about Scottish influence on a Labour government if there was to be such a pre-election deal.

The Tories, he said, had used these tactics to a "remarkable effect" during the 2015 General Election after Nicola Sturgeon said the SNP wanted to help "lock out" David Cameron from Downing Street in the event of a hung parliament.

"Should we form a pact with them?" he responded to this newspaper. "No, for this reason, one fundamental difference is the constitution question, but actually on many other issues I'm sure we've got a lot in common."

Mullin, who served in the foreign office and also as an international development minister, said the demise of Labour in Scotland meant it was unlikely the party could win an overall majority at Westminster at the next election.

He said: "As far as the loss of Labour seats in Scotland is concerned, I naturally regret that and it does have implications for the whole of the country and not just for Scotland. Because one of the consequences of that is that it's extremely difficult, it's going to be extremely difficult in the foreseeable future, for any party that's not the Conservative party to get a majority in the UK.

"But it's not impossible. It did happen in 1945, in 1966 and certainly 1997 and 2001. It was possible to form a government without Scottish MPs support, but I don't think it's possible any more.

"The only circumstances in which I could see is if there was a Liberal Democrat revival in England and there needs to be, frankly."

It was conceivable that if Labour had a majority of seats, but not an overall majority, that with the support of the Liberal Democrats they could form a government.

"It might even be a minority government. Then the Scottish nationalists would have option of bringing it down, as they did when they brought us Mrs Thatcher in 1979, or sort of giving it a tacit support."