If you want the real thing you'll have to travel to the top of the North Sea. Simon Heptinstall has a good yarn about a world-famous cottage industry

Fair Isle? Is it a real place or somewhere invented by the Marks & Spencer marketing department?

Fair Isle? Is it a real place or somewhere invented by the Marks & Spencer marketing department?

It's real enough – in fact it is Britain's most remote inhabited island. But it is so small (three miles by one) and so awkwardly positioned (on its own midway between the Shetlands and Orkneys), that it is often omitted from UK maps.

So how does anyone get there?

It can take as long as getting to Australia – and can cost as much, too. First you have to get to Shetland, then continue by plane or boat. The 25-minute Loganair flight from Shetland Tingwall to Fair Isle in a tiny, bumpy, eight-seater Islander aircraft is a memorable experience. Especially if you sit next to the chirpy pilot Eddie Watt, who points out sights such as his house and boat along the way. He even offered to swoop down to let me take pictures.

Hmmm, sounds err, a little too thrilling. Is there an alternative?

Fair Isle's special constable, Jimmy Stout, skippers the mail boat, the Good Shepherd, to and from Sumburgh or Lerwick up to three times a week. That costs just £2.30 and takes two-and-a-half or four-and-a-half hours. The 25 miles of open sea between Sumburgh Head and Fair Isle is notoriously choppy and after I watched green-faced passengers being helped off I decided to fly. Fog frequently means the flights are cancelled, while storms frequently mean the boat is cancelled. Sometimes the island is simply cut off.

So how come everyone has heard of such a tiny place?

It is a marvellous quirk of history that this tiny island with 70 inhabitants has a world-famous brand name. The islanders' traditional knitting style is more famous than the place itself. Some say it was influenced by the crew of a wrecked Spanish Armada ship in 1588, others by passing Baltic fishermen. Whatever, it is a distinctive series of knitted shapes including island icons such as anchors, rams' horns, ferns and flowers. Originally, the colours came from combining the variations in sheep's wool – white, grey, black, brown, red, ochre – with natural plant dyes such as lichen and amphibious bisort (don't ask).

But aren't Fair Isle jumpers the dreadful things Ronnie Corbett used to wear on his TV Christmas special?

That Val Doonican type of thing was more of a simple Nordic style than classic Fair Isle, which has a more delicate pattern and subtle colours. The trouble is that anyone can sell a Fair Isle-style sweater. "Fair Isle" has become a generic term for any brightly coloured jumper. There is no quality control, unless you see the extra words "made in Fair Isle". Only then are you getting the genuine article. And even this confirmed fleece-wearer found that when you see the real Fair Isle knits up close, hand-knitted using ancient patterns and local wool, they are definitely desirable quality items.

Where can I see one?

Only on Fair Isle. No shop anywhere sells the genuine thing. You can buy them at one of the knitters' houses or by mail order. When a cruise ship passes, the knitters put on a small display in the village hall. As a solo tourist, I had to call round to see Jimmy Stout's wife, Florrie. She keeps the world's unsold stock of genuine Fair Isle knitwear in her spare room.

It sounds like ye olde genuine cottage industry?

It's alarmingly small-time for such a massive brand name. There are four part-time knitters working on hand frames. They produce only about 100 sweaters a year.

Why do they carry on making them?

Well, they do cost more than £100 a time, so it's a handy income in a community where there are no ordinary nine-to-five jobs. The islanders are proud of their knitwear heritage. There is a wonderfully home-made museum with some fantastic examples of the knitting through the centuries and period advertising material, including a 1920s model trying to look seductive in a bizarre Fair Isle knitted hat.

Why else does anyone go there?

There are 70 people, 1,000 sheep and 150,000 seabirds, some of which are very rare. The Fair Isle bird observatory is famous in the birdwatching world. I'm no ornithologist but Bill Oddie has been there, so it must be good. The observatory staff will take visitors on a fantastic cliff walk to sit among the puffin colony and be terrifyingly dive-bombed by territorial skuas. The observatory is also the island's hotel, (sleeping 33), café and bar.

Anything else to do?

Surprisingly, I was really busy. It takes two days to walk the island's coastline, a spectacular series of cliffs and bays. There are two lighthouses, a quirky shop, harbours and beaches. I even found myself joining in unloading supplies from the mail boat. As well as the knitters, there are dozens of craftspeople only too pleased to show you what they make, from violins to stained-glass.

So how do I get there?

British Airways (0845 77 333 77; www.ba.com) flies from London and regional airports to Sumburgh, on the Shetlands, from £377 return. Regular overnight ferries from Aberdeen to Lerwick, on the Shetlands, are operated by P&O Scottish Ferries (01224 572615; www.poscottishferries.co.uk) until 30 September, and NorthLink Ferries (0845 6000 449; www.northlinkferries.co.uk) from 1 October, with fares from £53 return. From Shetland, Loganair (01595 840246; www.loganair.co.uk) flies from Tingwall (near Lerwick) on Mondays, Wednesdays, Fridays and Saturdays, and from Sumburgh once on Saturdays. Fares cost from £60 return.

For further information on Shetland, contact the tourist board (01595 693434; www.visitshetland.com). To buy a Fair Isle sweater, contact Linda Grieve, Fair Isle Crafts, Auld Haa, Fair Isle, Shetland, ZE2 9JU (01595 760264; www.fairisle. org.uk/ fairislecrafts) for price list and order forms.