By Andrew Osborn
LONDON (Reuters) - Prime Minister David Cameron will make an emotional appeal on Friday for Scotland to remain part of the United Kingdom, warning Scots a vote for independence would undermine Britain's image and standing in the world.
Speaking in London, Cameron, an Englishman whose Conservative party has only one of 59 UK-wide seats in Scotland, will make one of his most passionate defenses yet of the UK, which comprises England, Scotland, Wales and Northern Ireland.
"We would be deeply diminished without Scotland," Cameron will say, according to a note released by his office.
"If we lost Scotland, if the UK changed, we would rip the rug from under our own reputation. The plain fact is we matter more in the world together," he will tell an audience at the park used to host London's 2012 Olympic Games.
Scots will decide in a referendum on September 18 whether their nation, which has a population of just over 5 million and is a source of North Sea oil, should end its 307-year-old union with England and leave the UK.
A "yes" vote would place the future of Britain's Scotland-based nuclear submarine fleet in doubt and could weaken London's claim to a permanent seat on the United Nations and its influence in the European Union. EU People familiar with the matter say Cameron doesn't want to go down in history as the prime minister who lost Scotland. But he has conceded that his privileged background and centre-right politics mean he isn't the best person to win over Scots, usually more left-wing than the English.
RESULT "UP IN THE AIR"
Polls show Scots would vote to reject independence if a vote were held today, with only around a third keen to break away from the UK. However, there are still many undecided voters and Cameron will say the outcome is "up in the air".
"There can be no complacency about the result," he will say.
He will evoke the spirit of the 2012 London Olympics as an example of how the UK's four nations work well together and say that Scotland already has a large measure of independence when it comes to health, education and policing matters.
Tapping into an opinion poll earlier this month which showed people in England and Wales want Scotland to stay in the UK, Cameron will urge the English, Welsh and Northern Irish to tell Scots: "We want you to stay".
Rory Stewart, a half-English half-Scottish lawmaker in Cameron's Conservatives, on Thursday launched a campaign to turn those words into something tangible, saying he aimed to get 100,000 people to form a human chain of light from the west coast of Scotland to the east coast of England on July 19.
The idea, he told Reuters, would be to try to get people from all over the UK to show Scots - in dramatic fashion - that they wanted them to stay.
"The symbolism behind this would be to show the English, Welsh and Northern Irish love for Scotland. If we can't do that then Britain is in a sorry state."
(Editing by Tom Heneghan)