You may not be a Campbell or a MacLean, but you still have every right to wear a tartan, says Susan Irvine
In 1831, John Pinkerton, eminent Scottish historian, vented his spleen against one of his country's most beloved traditions: tartan. "Nothing," he wrote, "can reconcile the tasteless regularity and vulgar glow of tartan to the eye of fashion, and every attempt to introduce it has failed."

He was wrong then, and boy, is he wrong now. Tartan was a fashion triumph of the 19th century, and has raised its harlequin head at regular intervals in this one. Right now, for instance, plaid is one of the key themes for winter and into next spring. Ralph Lauren's tartan minikilts and jackets, shown with berets sporting a Celtic cockade, have already spawned a host of imitators. And for next spring, other designers have joined the clan, with Isaac Mizrahi whipping up a "Mcrahi tartan" in col ours of a"vulgar glow" to send Pinkerton into apoplexy.

Just what is it about Scotland's misty ancestral past that attracts two New Yorkers of Jewish descent, and what makes them think they have the right to tamper with a small, ethnic community's rightful heritage? Well, everything. I doubt Lauren and Mizrahi are aware of it, but tartan has a short and, dare I say it, chequered past. The kilt, its most famous incarnation, was invented by a Sassenach in the 18th century. Tartan as we know it is no more representative of the Scotland of old than square sausages and the White Heather Dance Troupe.

From its very beginning, tartan was the chosen garb of romantic dreamers longing to identify with a fictive past more glorious and golden than their present. Every reason then, for Ralph Lauren, the ultimate purveyor of manufactured heritage, to adopt i t as his own. As a symbol, tartan is usually flexible. In the world of Ralph Lauren, it stands for ruined castles, Flora MacDonald and all things Scots baronial. In the hands of the ethnic, rather than aristocratic, plunderers such as Jean Paul Gaultier,it refers to the tribal past of the untamed Highlander, Britain's equivalent of the Eskimo or Tibetan nomad. This kind of "authenticity" has become popular with streetwise clotheshorses in the light of our Nineties version of the 18th-century cult of the Noble Savage.

But seekers after authenticity need not apply for anything tartan, especially a kilt. For the Scottish kilt is actually the Lancashire kilt, invented by a Quaker industrialist called Thomas Rawlinson. In 1727, he made a contract with the chief of the MacDonells of Glengarry for the lease of a wood. Here he built a furnace for smelting ore shipped up from his home in Lancashire. Noticing that his Scots labourers were wearing little more than a big checked blanket, hardly ideal for heavy smelting, he decided to modify it.

Poor men of the day could not afford the expense of trousers, or trews, so Rawlinson sent for a regimental tailor to cut down a plaid blanket into a wee skirt or filibeg. A true fashion leader, he donned it himself and his associate, Ian McDonnell, foll o wed suit. McDonnell's clansmen then obediently copied their chieftain, starting a fashion that was to run and run through the past 270 years.

Instead of a kilt, what Highlanders actually wore through the centuries was a breacan, or belted plaid. This was basically a huge shawl or blanket, slung across one shoulder and gathered in folds at the waist with a belt. The remainder then hung down in pleats forming a skirt effect. What this was made of in the mists of time is uncertain, but by the 16th century, it was a rudimentary type of tartan. For dandies of the upper classes, tartan came criss-crossed with bold colours, and was wor n over trews.But for the ordinary clansman, plaid was mainly of brown and russet checks and worn over nothing more than a loose shirt, due to poverty.

Edward Burt, an English officer posted to Scotland in the 1720s, describes this particular way of wearing the plaid as the "quelt". These first quelts were minikilts that came to mid-thigh, and they already boasted a certain Scottish sauciness. This "pe t ticoat," wrote Burt, was "so very short that on a windy day, going up a hill or stooping, the indecency of it is plainly discovered".

To this day, a true Scotsman wears nothing but the good Scots air under his kilt. Liam Neeson, a Celt though not a Scot, is rumoured to play it by the book in Rob Roy (due to be released end of April), the film of the Scottish hero made famous by Sir Walter Scott's book. Neeson may be one man you hope will not win his battles with the blustery Scottish wind but you will have to see the film to find out. The Highlanders in Rob Roy, interestingly wear an approximation of the genuine breacan rather than the pseudy kilt, and in drab colours rather than the clan tartans we consider gospel.

Clan tartan, a different pattern allotted to a specific family as a birthright, is yet another creation of the Romantic imagination; a form of fanciful dress and national yearning. Its destiny was assured by the creation of the Highland regiments after the 1745 uprising, a ploy by the elder Pitt to channel Highlanders' martial tendencies in the interests of the English. The regiments each took to wearing a distinctive tartan, launching the "tradition" for clan tartans that most Scots believe goes back to the Dark Ages. Tartan trews, as worn by the Highlander upper classes for some generations before that, are actually a more genuine form of Scottish national dress than the kilt, which is basically a bizarre transvestite travesty of Scottish history.

All this is tragic news for a Scot but good news for fashion. As a sentimental Scottish lass who snivels whenever football crowds break into "Flowers of Scotland", I am devastated to discover the kilt's false heritage. And deep down, I am determined to disprove the evidence, laid out with typically wicked relish by the historian Hugh Trevor-Roper in his essay "The Highland Tradition of Scotland".

Until then, however, as a fashion victim, I can but revel. This means my Joseph minikilt is as "genuine" as a £400 job made up in Edinburgh for a rich Yank. It means no Scotswoman need have qualms about sporting Givenchy's "Caledonian Airlines" plaid su i t next spring. And it means I need never feel obliged to lay tartan carpets in my London flat in homage. Och weel, here's a birl of my mini-kilt to the King over the Water.