Scottish independence increasingly looks like an iceberg that could sink Prime Minister David Cameron’s government and the opposition Labour Party. And like the passengers on the Titanic, they never saw it coming.

Yesterday’s YouGov Plc poll putting the Yes vote on 51 percent sparked a fresh effort from supporters of the union to urge Scots to come back from the brink. About 100 Labour lawmakers will travel to Scotland this week to campaign for a No vote, while Conservative Chancellor of the Exchequer George Osborne offered more powers over taxes and spending to the Scottish Parliament -- if voters opt to stay part of the U.K.

Cameron was staying with Queen Elizabeth II at Balmoral Castle in northeast Scotland when he learned that the independence campaign had moved into the lead.

“I’ve always said that the polls will narrow -- it’s clearly very tight,” Alistair Darling, the leader of the Better Together campaign, which opposes independence, told the BBC.

“This is something that’s dividing families, friends.” Scottish independence would bring the curtain down on a 307-year-old union that created one of the most influential countries in the world. It would also constitute the biggest crisis of Cameron’s premiership.

Eoin Treacy's view

Poll results are within the statistical margin for error and with turnout likely to be high the Scottish vote on independence is forcing investors to reassess their exposure.

This is particularly evident in the Sterling spot rate (Cable) The Pound hit a new six year high in July amid speculation that the interest rate differential would widen in the UK’s favour. However since then, the decline of the Euro and the flow of news regarding the Scottish independence vote have contributed to a marked decline which was further extended today. With 10 days before the vote, this may be a case of sell the rumour buy the news but a clear upward dynamic will be required to check the slide.