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* Sterling drops, shares fall, banks brace for Scotland vote
* Britain scrambles to offer more powers to Scots
* Unionist campaign criticised as negative and complacent
* Nationalists claim momentum ahead of Sept. 18 vote
By Guy Faulconbridge and Angus MacSwan
LONDON/EDINBURGH, Sept 8 (Reuters) - The British pound slidand the stock market shuddered on Monday after an opinion pollshowed for the first time that Scots may vote for independencenext week in a referendum that could herald the break up of theUnited Kingdom.
The survey prompted concern bordering on panic amongBritain's ruling elite, with Prime Minister David Cameron'sConservative-led government promising proposals this week togrant Scotland greater autonomy if it stays.
Cameron's job would be on the line if Scots vote on Sept. 18to secede, less than eight months before a national electionplanned for May. His spokesman said on Monday the government wasnot making contingency plans for the possibility of Scottishindependence.
Sterling fell more than 1 percent - its biggest one-day dropin 13 months - to $1.6145 in early European tradingwhile more than 3 billion pounds ($4.8 billion) was wiped offthe market value of five London-listed companies with largeexposure to Scotland.
"The speed with which the polls have flipped has clearlybeen a shock to a lot of people," said Adam Myers, European headof FX strategy at Credit Agricole in London.
After months of polls showing nationalists heading fordefeat, the survey by the respected YouGov pollster raised thereal prospect that secessionists could achieve their goal ofbreaking the 307-year-old union with England.
If Scots voted to leave the United Kingdom, Cameron wouldface calls to quit before the general election, while theopposition Labour party's chances of gaining a majority could bescuppered if it lost its 40 Scottish lawmakers.
Cameron, who visited Queen Elizabeth in Scotland on Sunday,has insisted he will not resign. British media quoted a palacesource as saying the monarch was concerned and had asked fordaily updates on the situation.
A vote for independence by Scotland's 4 million voters wouldbe followed by negotiations with London on what to do about thepound, the $2.1 trillion national debt, North Sea oil and thefuture of Britain's nuclear submarine base in Scotland ahead ofindependence pencilled in for March 24, 2016.
BETTER TOGETHER?
With less than two weeks to go before the Sept. 18 vote, thepoll put the "Yes" to independence campaign on 51 percentagainst "no" camp on 49 percent, excluding undecided voters,overturning a 22-point lead for the unionist campaign in just amonth, the Sunday Times said.
Less than 12 hours after the poll was released, Britain'ssecond most powerful man promised on national television thatplans would be set out to give Scotland more autonomy on tax,spending and welfare if Scots vote against independence.
"You will see in the next few days a plan of action to givemore powers to Scotland," finance minister George Osborne said.
"Then Scotland will have the best of both worlds. They willboth avoid the risks of separation but have more control overtheir own destiny, which is where I think many Scots want tobe," Osborne told the BBC.
But the comments were cast as panic by Scottish FirstMinister Alex Salmond, leader of the Scottish National Party(SNP), who said the campaign to save the union was spirallinginto self-destruction.
He scoffed at last-minute offers of greater autonomy forScotland from London parties, saying: "I've no doubt they'llcobble together something because having failed to scare theScottish people, the next step is to try to bribe us."
The polls have tightened dramatically as undecided votersmake up their minds after Salmond appeared to trounce "No"campaign leader Alistair Darling in a television debate andScots were irked by a perceived scare campaign by unionists.
Labelled "Project Fear" by nationalists, the unionistcampaign has drawn criticism from many unionists who say it hasbeen complacent, negative and riven by divisions.
"The campaign so far has been narrow and negative," saidHenry McLeish, a former Scottish first minister from the Labourparty. "It's also been patronising and its really lackedemotion, lacked passion and lacked soul so therefore in acountry like Scotland where the heart and head are to be takentogether, that's been a major deficiency."
Salmond has scored well with Labour supporters and women,convincing many that the economic arguments are not as dire asdepicted by his adversaries, polls show.
With Cameron's Conservatives unpopular in left-of-centreScotland, the "No" campaign is turning to former Prime MinisterGordon Brown as its main hope of turning the tide.
Touring Scotland to rally the unionist vote, Brown declared:"The truth is Scots would be entering an economicminefield under the SNP's economic plans for separation."
KNIFE EDGE
British newspapers headlined the biggest domestic threat tothe United Kingdom since Irish nationalists created a breakawayrepublic almost a century ago.
"Scots vote chaos - Jocky Horror show," read the front pageof the Sun, Britain's most read daily, while the right-wingDaily Telegraph declared on "Ten days to save the Union".
In Scotland, the pro-union Scotsman cautioned against apanic reaction.
"When Scotland's future is on a knife edge and Westminsterpolitics is facing altercation, calls for calm may struggle tobe heard. But whatever the referendum result, calm there must beif reason is to prevail and panic not to take over," it said.
Britain's benchmark FTSE 100 index fell after theYouGov poll. Five of the top 10 falls were companies connectedto Scotland - Lloyds Banking Group, Royal Bank ofScotland, Standard Life, energy group SSE and engineering firm Weir group.
Banking industry sources told Reuters last week that Lloydsis considering moving its registered offices to London if Scotsvote for independence. RBS is also examining its options.
The two banks have warned that an independent Scotland wouldpresent a significant risk to their businesses, impacting theirfunding, tax and compliance costs.
Nationalists accuse London of squandering Scottish wealthand say that Scotland would be one of the world's richestcountries if it took control of its own destiny.
Unionists, including Britain's three main political parties,say the United Kingdom is stronger if it stays together and thatScottish independence would bring significant financial,economic and political uncertainty.
"I can see why Scottish people would want more say in theirlives," said Jim O'Neill, the English-born former chairman ofGoldman Sachs Asset Management. "But from where I sit, itdoesn't really make a lot of sense nationally." (1 US dollar = 0.6194 British pound) (Additional reporting by Sarah Young, Kate Holton, KylieMacLellan, Patrick Graham, Matt Scuffham and Atul Prakash)
