British leader Cameron implores Scots not to break his heart by leaving the United Kingdom

Prime Minister David Cameron abandoned party politics for pure emotion Wednesday, imploring Scots not to break his heart by voting to become independent from the United Kingdom.

Conservative Party chief Cameron, Labour leader Ed Miliband and Liberal Democrat chief Nick Clegg all pulled out of a weekly House of Commons question session in London to make a late campaign dash to Scotland as polls suggest the two sides are neck-and-neck ahead of next week's independence referendum.

"I would be heartbroken ... if this family of nations is torn apart," Cameron told an invited audience at the Edinburgh headquarters of the Scottish Widows insurance firm.

Cameron's Conservatives are deeply unpopular in Scotland. Many independence supporters cite his government's budget-slashing policies as one reason they want to end Scotland's 307-year-old union with England.

Scottish nationalist leader Alex Salmond said visits by unpopular London-based politicians could only help his Yes campaign.

"If I thought they were coming by bus, I'd send the bus fare," he said.

Cameron acknowledged his unpopularity, but said the vote was not about giving "the effing Tories" a kicking.

"This is not a decision about the next five years," he said. "This is a decision about the next century."

He has ordered the blue-and-white Scottish flag to be flown over his office at No. 10 Downing Street until the vote in a sign of support for Scotland's place in the union.

The close race ahead of the Sept. 18 vote has sent shudders through the financial markets.

The pound and shares in Scotland-based financial institutions have sagged amid uncertainty over what currency an independent Scotland would use and whether businesses and capital would flee across the border.

Financial group Standard Life added to the jitters, announcing Wednesday it was ready to move parts of its business to England if Scotland votes for independence. Standard Life employs 5,000 people in Scotland and has been based there for 189 years.

In a statement to shareholders, the company said "in view of the uncertainty around Scotland's constitutional future, we have put in place precautionary measures which would help enable us to provide customers with continuity."

The measures include transferring pensions, investments and other long-term savings to England to ensure they remain part of Britain's currency and tax regime.

Jill Lawless reported from London.