The final countdown: yes/no battle for votes in Scotland

Mr Cameron said he would be “utterly heartbroken” if Scotland voted to leave the UK, and issued a warning that Thursday’s referendum was a “once and for all” decision as he made a last-ditch trip north to urge voters to save the union.

Speaking in Aberdeen,the prime minister warned that if Scots voted for independence it would result in a “painful divorce”. He said: “On Friday, people could be living in a different country, with a different place in the world and a different future ahead of it.

“This is a decision that could break up our family of nations, and rip Scotland from the rest of the UK. And we must be very clear. There’s no going back from this. No re-run. This is a once-and-for-all decision.”

Scottish First Minister Alex Salmond, said he was confident the yes campaign would win.

Speaking at Edinburgh Airport he also repeated his allegation that the Treasury leaked information to the media over RBS’s plans to relocate its headquarters to England if there is a yes vote.

His comments come after a number of banks, businesses and leading retailers voiced their concerns over independence.

‘Scaremongering campaign’

Mr Salmond said: “When you try to pressurise people, pressurise companies, as the prime minister has undoubtedly been doing and indeed the Treasury, then that’s a different circumstance.

“I think people in Scotland will know the prime minister’s fingerprints are all over the scaremongering campaign and the Treasury’s fingerprints are all over the bank campaign.”

Mr Salmond added: “This is said to be David Cameron’s last campaign visit to Scotland. The next time he comes to Scotland it will not be to love-bomb or engage in desperate last-minute scaremongering, and following a yes vote it will be to engage in serious post-referendum talks in the best interests of the people of Scotland and the rest of the UK, as pledged in the Edinburgh Agreement.

“From our side, those talks will be taken forward with a Team Scotland approach, involving people on a cross-party basis encompassing talents from across the spectrum.”

Downing Street confirmed that Mr Cameron’s trip to north east Scotland was expected to be his final visit north of the border ahead of Thursday’s vote. He is expected to spend the day of the referendum working in 10 Downing Street, said his official spokesman.

‘No comment ‘ on the Queen

Asked whether Mr Cameron welcomed the Queen’s reported comments that she hopes Scots will “think very carefully about the future” before voting, the spokesman said: “I wouldn’t have a comment to make on those.”

The spokesman said the government’s position remains that it is not making any contingency plans for the possibility of a yes vote, telling a regular Westminster media briefing: “The focus is on making the case and making the arguments.

“The poll that counts is on Thursday, and that’s why the right thing to do is make the case through until then.”

With just three days of campaigning left, political leaders on both sides of the debate will be intensifying their efforts in a last-gasp attempt to win over undecided voters.

Three polls that were published on Sunday put the no campaign ahead – with a survey by Panelbase giving them a lead of just over one point when undecided voters are excluded. The survey, for The Sunday Times, put support for no at 50.6 per cent, narrowly ahead of yes on 49.4 per cent.

A rival ICM poll recorded an eight-point lead for the pro-independence campaign – but experts urged caution because of its smaller than normal sample size.

Better Together leader Alistair Darling said: “I’ve said before this is going to go down to the wire but I think we will win because I don’t think Scotland is going to get bullied into accepting something that it doesn’t want.”