Even Smiths and Clarks can lay claim to Celtic roots.
Cotla-Gearr may sound like ventriloquism, but it is what style- conscious bridegrooms and wedding guests are wearing north of the border. And now south of the border, since the films Braveheart and Rob Roy have had many of us rushing to check out our celtic links.

A Cotla-Gearr is a Highland jacket, invariably worn with a feile (kilt), a sporran (originally designed to carry wilderness rations of oatmeal and a metal plate), ghillie brogues (laced pumps) and hose sporting garter flashes and possibly a sgian-dubh, a small knife tucked into the welt.

A lacy jabot shirt completes the basic kit although Jane Pattie, a clan aficionado who has worked for The Scotch House in London and Edinburgh for 20 years, considers a plain evening shirt more stylish.

Jane currently works in the Tartan Room at the company's Knightsbridge branch which holds around 230 clan tartans, although a total of 700 can be ordered from their Scottish suppliers. This includes a large range of flame-retardant upholstery tartans at pounds 39.50 per metre.

"Our best-sellers have always been Black Watch and Royal Stewart," says Jane, "but since the films, business has almost doubled and we're selling a lot more clan tartans."

Searching the directory for my own pattern, or sett, I found two - clan and hunting; most clans have at least these two options. If you want to make your own kilt (though many young male customers simply throw a length of plaid over their shoulder, Liam Neeson-style) you will need 3.70m of double-width fabric at around pounds 25 per metre. Most customers opt to have their kilts made up for them. For 37 years the Scotch House has been sending this work up to a Scottish couple who run their own business.

The work is painstaking, with deep pleats hand-stitched to exactly match the pattern repeat. Even the belt loops blend in.Since kilt fabric can weigh anything from 8 to 16oz per metre, and an average kilt uses eight metres, spare fabric is trimmed inside and the garment lined with calico.

"Even so a kilt can add four inches to your hips," warns Jane, "so most women opt for a more fitted kilted skirt instead, especially as, historically, full kilts are only worn by men. Kilted skirts are obviously cheaper than kilts - pounds 150 compared with pounds 425.

Authentic kilt-making is an apprenticed craft, as I saw when I visited the workroom of Daiglen Traditional Kiltmakers and Highland outfitters, tucked away at the foot of the Ochil Hills in the heart of Clackmannanshire's woollen mill country. Off the tourist trail, local people and ex-pats alike make their way to a side street in Tillicoultry, where kilts and jackets are made to measure on site. When you see the expertise involved, pounds 215 for a medium weight kilt sounds like a bargain.

You don't have to be a Mac to have a clan - Smiths, Clarks and Elliotts all have a tartan. But if you do not, or have fallen out with your relatives, one of the newer, general-purpose setts might suit. In 1934 the National Association of Scottish Woollen Manufacturers came up with a general purpose red and green tartan they called National. Sixty years later McCalls designed and registered the Scottish National Dress Tartan, dark green with a wide white strip. (Though perhaps most versatile of all is the Welsh kilt, made from plain black native wool and longer than the Scottish or Irish versions.)

New tartans are being invented all the time (including, inevitably, a Braveheart).There is a Mother's Pride tartan, created to adorn 7000 teddy bears for a promotional campaign; a bright blue Nuclear Fuels job, typical of the boon in corporate and commercial tartans launched over the past five years; and a yellow McDuck tartan, as worn by Scrooge McDuck, uncle of Donald, and drawn up by Walt Disney in 1942.

The Scottish Tartans Society, which holds a register of all publicly- known tartans, drew the line, however, at a Jesus Christ tartan, designed in all seriousness by an American. Christ could have had a tartan, though. During the Roman occupation the early Celts were noted for their woollen cloth coloured with plant extracts. This subtle shading was largely lost with the creation of aniline dyes. However, as a kilt can last several generations if moth-proofed, modern dyes do ensure that the colour lasts.

Even though many of the pre-Culloden setts have been lost, there are still around 2,500 tartans, increasing at the rate of about 40 a year. Most date back at least 100 years but, perhaps surprisingly, the new upstarts are largely welcomed on the grounds that anything in tartan, even a cartoon character or a sales rep, publicises Scotland.

Being a conscientious journo, I asked the $64,000 question, (being careful not to phrase it "Is anything worn under a kilt?" to which the answer is "No, everything's in perfect working order!"). Apparently the fashion- conscious Highlander opts for natty tartan briefs known as Nessies.

Daiglen Traditional Kiltmakers and Highland Outfitters, 27 Stirling Street, Tillicoultry, Clackmannanshire FK13 6EB (01259 750440).

The Scotch House, 2 Brompton Road, London SWIX 7PB (0171-581 2151) and 39/41 Princes Street, Edinburgh (0131-556 1252).