Scottish independence: Britain faces 'constitutional crisis' at next election

Polls show MPs from north of the border could sweep Labour to power in 2015 – even if Scotland has already voted to become an independent country

Labour leader Ed Miliband with Liverpool City Council leader Joe Anderson, raising a Saltire on Liverpool waterfront on Tuesday (PA)

Ministers are under pressure to explain how they would respond if Scots vote for independence, as it emerged that Labour is on course to win the general election only because of its strong support in Scotland.

The latest “poll of polls” for The Independent suggests that Ed Miliband will win an overall majority of 32 next May. But if Scottish MPs are excluded, there would be a hung parliament, with Labour three seats short of a majority.

“Scotland is potentially critical to Labour’s ability to win an overall majority,” said John Curtice, professor of politics at Strathclyde University, who compiled the data. At present, Labour holds 41 of the 59 Scottish seats at Westminster and could land another five if the latest polls are reflected next May. Labour is on 35 per cent, the Conservatives 31 per cent, Ukip 13 per cent and the Liberal Democrats nine per cent.

Some Conservative MPs want Scottish voters excluded from the general election if the country decides to break away. The Scottish National Party has called for the election to be postponed so it did not disrupt negotiations before “independence day” in March 2016.

Whitehall sources said that delaying an election for the first time since the Second World War has not been discussed by ministers. But one official admitted: “It is too sensitive before the referendum, but we couldn’t duck it any longer if there were a Yes vote.”

Senior MPs in the three main parties said postponing the election would be “very unlikely”. They fear it would be condemned as “anti-democratic” and a “constitutional outrage”, and would be a gift for Ukip.

John Redwood, the former Tory Cabinet minister, said Scots should not participate in next year’s election if they vote to leave the UK. He argued the election should take place as normal elsewhere, with existing Scottish MPs allowed to remain until independence.

The Scottish flag flutters next to the Union flag over Downing Street in London (Getty)

“Scottish MPs would only serve for less than a year and should not take an active part in non-Scottish matters. That seems to me the neatest solution,” he said.

Peter Riddell, director of the Institute for Government think tank, said the position would be “dangerous and unsustainable” if Mr Miliband won an overall majority due to Scottish MPs, presenting Labour with a “hellish” dilemma.

But Graham Allen, Labour chairman of the Select Committee on Political and Constitutional Reform, insisted that Labour would simply move from having an overall majority to requiring the support of other parties. “The numbers in the House of Commons would decide who the Government is,” he said.

David Cameron, Ed Miliband and Nick Clegg will all hit the campaign trail in Scotland tomorrow, instead of appearing at Prime Minister’s Questions in an attempt to arrest the slide in support for a No vote. After the idea was suggested by Mr Miliband, Mr Cameron agreed to tear up his diary. The three leaders will travel separately and campaign in different parts of Scotland but their message will be the same: “We want you to stay.”

Alex Salmond, the First Minister, said: “The message of this extraordinary, last-minute reaction is that the Westminster elite are in a state of absolute panic as the ground in Scotland shifts under their feet.”

Today Gordon Brown spoke movingly as he vowed to "nail the SNP lie" that Scotland's health service is at risk of privatisation. Addressing activists in Glasgow, his voice wavered slightly as he spoke about his baby daughter Jennifer Jane, who died from a brain haemorrhage in 2002, and how his sight was saved after a rugby accident left him blind in one eye at the age of 16.

The former Prime Minister said: "I love Scotland, I love the NHS. When my daughter died it was as the result of not being able to do anything to save her life, and my respect for the NHS grew as a result of the experience that Sarah and I had.”

Mr Cameron ordered the Scottish saltire to be flown over Downing Street until next week’s referendum. But his gesture of solidarity with Scotland got off to an inauspicious start as the flag fell down the first time that workmen tried to run it up the flagpole.

* Writing in Wednesday's Daily Mail, Mr Cameron tells the Scottish people: "The choice for you is clear: a leap into the dark with a Yes vote, or a brighter future for Scotland by voting No. You can have the best of both worlds in the UK. You can have more powers in Scotland."

The Prime Minister says: "The UK is a precious and special country. That is what is at stake. So let no-one in Scotland be in any doubt: we desperately want you to stay; we do not want this family of nations to be ripped apart."

He adds: "If we pull together, we can keep on building a better future for our children. We can make sure our destiny matches our history, because there really will be no second chances. If the UK breaks apart, it breaks apart forever."