The ladies’ lavatory of Bella Italia in Central Edinburgh has three cubicles, the wall tiles are white with diagonal green stripes and the ceiling is grey chipboard. There is little to suggest that the site was of importance in the unification of England and Scotland and, even yesterday, few visitors were engaged upon pilgrimages.

But, according to Richard Finlay, of the University of Strathclyde, it was there, 300 years ago yesterday, that leaders of the old Scottish Parliament signed the Act of Union.

“They were processing along the Royal Mile towards Parliament,” Professor Finlay told The Times. “In the streets there was an angry mob, hounding the politicians who had betrayed the nation, so they took refuge in a cellar. And that’s the spot where it was signed.”

The house was rebuilt, but the basement remained. “I suppose there ought to be some sort of plaque,” Mary Rogers, 48, of Dublin, said. “Although the sense of history wouldn’t make me come here more.”

Shortly after lunch at the restaurant, Christine Constable, who is vice-chairman of the English Democrats, arrived with Scilla Cullen, chairman of the Campaign for an English Parliament. Both are in Edinburgh to take part in a televised debate on the Union. “Are you sure it’s here?” she asked, venturing through the door. “It looks like it has been the victim of a 1960s makeover. It’s the perfect metaphor for the scenario we are in now, bound by an Act that was appropriate at the time but isn’t any longer.”

Manuel Biondi, deputy manager of Bella Italia, is delighted that his lavatories are so important, but many historians dismiss the story as folklore. According to Cassell’s Old and New Edinburgh, a periodical in the 1880s, the Lord Chancellor of Scotland, the Earl of Seafield, with the Royal Commissioner, the Duke of Queensbury and fellow parliamentarians, ducked into “a cellar of a house, No 177 High Street” where “one half of the signatures were appended to the treaty”. That cellar is now the lavatory. The historian Michael Fry believes that the Scottish Cabinet signed in the stone summerhouse of an aristocratic residence. Professor Allan Macinnes, whose book Union and Empire: The Making of the United Kingdom of 1707 is due out in the summer, is disinclined to believe either story.

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