Scotland independence: U.K. leaders make late campaign dash

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Critics noted that Cameron did not risk speaking before an uninvited audience of Scots on the street.

Cameron's Conservatives are deeply unpopular in Scotland. Many independence supporters cite his government's budget-slashing policies as one reason they want to leave the United Kingdom.

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.

Vote 'about the next century'

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."

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Cameron 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 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."

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

Salmond's pro-independence Scottish administration argues that North Sea oil revenue, much of it in Scottish waters, will underpin the prosperity of an independent Scotland. Others say that view is based on an optimistic assessment of how much oil remains.

The chief of the oil giant BP said Wednesday that remaining reserves were "smaller and more challenging to develop than in the past."

"Future long-term investments require fiscal stability and certainty," BP CEO Bob Dudley said. "As a major investor in Scotland now and into the future BP believes that the future prospects for the North Sea are best served by maintaining the existing capacity and integrity of the United Kingdom."