PRO-UK campaigners have been warned not to "undermine Scotland" by veterans of the fight to keep Quebec in Canada.
Senior figures in the victorious campaigns against sovereignty for the French-speaking province believe their British counterparts are risking defeat by being overwhelmingly negative.
Some, The Herald understands, have passed their concerns on to Scottish Unionist politicians.
They include Dennis Dawson, a Canadian liberal senator and major player in the independence referendums of 1980 and 1995. Mr Dawson said he had met Better Together figures over wine during parliament exchanges.
"I told them 'Don't undermine Scotland'," he said. "Scotland could be independent as much as the other 180 countries in the UN. But does it need to be?
"You can't say that Scotland does not have the economic force to be independent. That is the wrong thing to say.
"Nobody can prove an independent Scotland would be more prosperous. But nobody can prove it would be in economic turmoil either."
Mr Dawson believes the danger in his country - and his province - was always running down Quebec, risking a backlash from voters.
He said: "It is quite clear the biggest risk that the No side have always taken in Canada was to oversimplify the negative aspects of independence.
"The 'No' does have much more choice than having the negative campaign because you are asking people to vote No to something. But you can have campaign that is oriented on the fact that Canada offers more opportunities than problems.
"But people like the status quo. So if it ain't broke, don't fix it."
Better Together has always denied that it is exclusively negative - and dismissed claims its pro-independence opponents are more positive.
In recent weeks the UK Government has issued stark warnings about the future of the Scottish economy while one prominent Labour ex-minister, George Robertson said independence would be "cataclysmic" for the entire western world.
The pro-UK movement, meanwhile, has sought to learn from Canada, recently adopting the slogan No Thanks, thought to have been inspired by Quebec's "Non Merci" of 1995, and studying last-ditch efforts by Anglophones in neighbouring to "lovebomb" the would-be breakaway province.
Edward Goldenberg, chief of staff to Jean Chretien, Canada's prime minister during the 1995 referendum, stressed the need to strike an emotional as well as a rational chord.
He said: "In 1980 the No camp talked a great deal about the advantages of Canada and the victory was 60-40. In 1995 there was less talk about the advantages of being Canadian and more about the economics and the result was closer. If the No side abdicates the heart, it will be more problematic to win."
Michael Keating, head of the Future of the UK and Scotland programme run by the Economic and Social Research Council, is a seasoned watcher of independence politics on both sides of the Atlantic.
He reckons Better Together and their allies are aware of the dangers of the kind of negative messages highlighted in Canada nearly two decades ago.
"The No camp have known this all along," he said. "They just keep forgetting. They should also learn that lovebombing from England doesn't work either. Any campaign has to be won in Scotland.
"The Canadians organised a big Unity rally in Montreal in the last days of the 1995 referendum. People may not have cared about it but it could have backfired."