All hail the Cool Caledonians

When Ewan McGregor hosted a Burns Night supper this week, he just confirmed what Katy Guest had been suspecting: that Scotland and Scottishness are now more fashionable than at any time since Queen Victoria's day London's Scottish diaspora turned out in force. But so did some of the celebrities for whom tartan is the new black. But, as Katy Guest discovers, there's nothing new in that

"Fair fa' your honest, sonsie face, Great chieftain o' the puddin' race!", as they'll be saying in London this evening. Because anyone worth their porridge in the capital tonight will be strapping on a kilt and celebrating Burns Night. Ewan McGregor and Sharleen Spiteri kicked things off on Wednesday with a charity ball at the trendy St Martins Lane Hotel, where Stella McCartney, Lady Helen Taylor and Mario Testino turned up, waving their Scottish family trees and preparing to draw skean-dhus over the vegan haggis. Tonight it's the turn of the Fleming-Wyfold Art Foundation, which is hosting a lavish Burns Night party to launch its inaugural exhibition, and the official Robert Burns World Federation, which is staging Ae Fond Kiss – a Scottish ballad opera.

It seems that this is the best time since the Victorian era to be Scottish. Ewan McGregor, riding on the success of the film of Irvine Welsh's Trainspotting, has become one of Hollywood's biggest box-office draws, and Monarch of the Glen is one of the BBC's biggest ratings winners. The footballer Ally McCoist stole the cool crown from Manchester when he was found to have stolen the heart of Patsy Kensit, the ex-wife of the formerly hip Liam Gallagher. J K Rowling has put Edinburgh on the map – although not, to the chagrin of the city's tourism officers, on Warner's Harry Potter tour map – by writing Harry Potter in its cafés.

As if that wasn't enough, there is a royal edge to this celebrity endorsement. It was Queen Victoria who developed Britain's taste for all things tartan, in the mid-19th century. Ranald MacDonald, the managing director of the Scottish Boisdale club in Belgravia – the only place to be in London on Burns Night – explains: "When Victoria visited Balmoral in the 1850s, she had all her subjects dressed in tartan. Most of them had never seen tartan before. It's something that came from the Highlands with the clan system and the kilt." Whereas the Highlands and the Lowlands had seen themselves as separate, often antagonistic races, these royal favours amalgamated them in the public imagination. "Now, you go into a Scottish tourist shop and find it full of tartans," continues Ranald. "The Scots have taken on board everything they once abhorred."

Today, fortunately for the Scots (although some will not see it like that), the country has been endorsed by another royal benefactor. St Andrews University, once famous for nothing more glamorous than Oxbridge rejects and golf, has seen its admissions applications rise by 44 per cent due to what it calls "the Prince William effect". According to sources at the university, the surge has been particularly notable in applications from young women, particularly from the United States.

This comes as no surprise to Ranald. "Scots are better looking and stronger, and a lot cleverer, too," he says. "Strictly speaking we're genetically superior."

As if it needed it, this modest claim has been backed by the new royalty, Madonna, who dredged up her husband Guy Ritchie's Scottish credentials to qualify her for a Scottish wedding. "My husband and I are both obsessed with history," she said, "and we wanted to go to a place that had history. It was truly magical. The Scots were great."

As in the past, it is the English and Americans who are obsessing about Scotland. The Scots, as a race, have never been great at self-promotion. Muriel Gray, on being made rector of Edinburgh University, said, "I am no staunch defender of the couthy heedrum-hodrum brand of marketable mock Scottishness". Irvine Welsh went further. In Trainspotting, he had his hero, Renton, rant that his friends are: "Failures in a country of failures. It's nae good blamin it oan the English for colonising us. Ah don't hate the English. They're just wankers. We are colonised by wankers. We can't even pick a decent, vibrant, healthy culture to be colonised by. No. We're ruled by effete arseholes. What does that make us? The lowest of the fuckin low, the scum of the earth. The most wretched, servile, miserable, pathetic trash that was ever shat intae creation. Ah don't hate the English. They just git oan wi the shite thuv goat. Ah hate the Scots."

The English, with typically naïve fortitude, don't take it personally. They have always been good at ignoring the antipathy that floods towards them from the north. Despite the fact that the Scots support whichever team is playing against England, those south of the border persist in taking the Scottish to their hearts.

Where will it end, this obsession with all things Scots? The fashion world is falling over itself to praise the talents of Alexander McQueen. The kilt has been taken up by everyone from Jean Paul Gaultier to Samuel L Jackson, who wore his on the Parkinson show. Companies such as Thomas Cook, Direct Line and Sky are already relocating their call centres north of the border because, we are told, we customers find the Scottish accent soothing and trustworthy. Are we about to find our country covered in a rash of Scottish theme pubs, all pre-fabricated in a factory outside Milton Keynes? Will we be hit by a wave of Angela's Tatties-style Scottish memoirs?

Charles Kennedy, the latest in a long line of eminent Scots who have dominated British politics for centuries, is optimistic about his nation's enduring image. "I think Scotland has always been cool," he says. "Although I suppose a cool politician is a bit of a contradiction in terms. Cool Britannia giving way to Cool Caledonia? Fine by me. I rather fancy the sobriquet 'Highland Trendsetter'. Who knows where it might lead?"