A jumper with salt in its seams

For three centuries the gansey was working clothing. Knitted by women in fishing villages from Cornwall to Shetland, from the Yorkshire coast to the Hebrides, it was made in the round on four or five steel needles with no seams at all — nothing to rub under a wet oilskin, nothing to split when a man hauled a net. The patterns mattered. Herringbone, cables, diamonds, moss stitch, anchors and initials were knitted into the yoke and chest, and families guarded their own combinations. A body recovered from the sea could, it was said, be identified by the stitches on his chest. Whether or not that happened as often as the stories claim, it tells you what a gansey was: not a fashion, but a signature.

Knitting one today is slow, deliberate work, and that is precisely the point. You end up with a dense, windproof jumper that softens with every wear and lasts for decades — and you learn a good deal about wool along the way.

Choosing wool that will last

The original ganseys were knitted from tightly spun, lightly oiled worsted yarn, usually in a natural grey-cream, navy or dark indigo. That tight twist is what gives the fabric its weather resistance: the fibres lie close together and the wind struggles to get through.

Look for a five-ply gansey yarn, or a well-twisted worsted-weight wool from a British breed. Good choices include:

• Bluefaced Leicester — fine, hard-wearing and with a gentle sheen that shows off cable work.
• Shetland — light, warm and slightly hairy, ideal for a softer everyday jumper.
• Wensleydale or Romney — long stapled and famously tough, the closest thing to the old working yarns.

Avoid anything fluffy, loosely spun or heavily processed if you want the traditional result. Buy enough in one dye lot — a gansey takes a lot of yarn, often 800 to 1,000 metres — and wind it into balls before you begin.

Tension, measurements and an honest swatch

Gansey patterns are knitted at a firm tension, typically seven stitches and nine rows to the inch over stocking stitch. Knit a swatch at least four inches square, wash it as you would the finished jumper and let it dry flat before you measure. Everything else depends on this number.

Then take the wearer's chest measurement and add two inches of ease for a traditional fit. If the chest measures 42 inches, you are knitting a 44-inch circumference. At seven stitches to the inch that is 308 stitches — round down to 304, which divides neatly by four for the welt.

Casting on and working the body

Cast on 304 stitches on needles a size smaller than your working needles. Join into a round, taking care not to twist, and work a two-by-two rib welt for two inches. Change to your larger needles.

Mark the sides of the body with a contrasting thread. Work plain for two or three inches, then begin your pattern panel across the centre of the front. A simple arrangement works well: a central cable of twelve stitches, flanked by moss stitch, with plain knitting to each side. Repeat the same panel on the back.

Continue straight until the work measures about sixteen inches from the cast-on edge, or two inches below the armhole.

Gussets, yoke and shoulders

The gusset is the gansey's secret. At each side, increase one stitch either side of the side marker every fourth round until you have about thirty extra stitches on each side. These give the roomy, comfortable underarm that makes a gansey so easy to wear.

When the body is long enough, slip the gusset stitches onto waste yarn. Work the front and back separately, back and forth in rows, up to the shoulders, keeping the pattern panels running straight. Cast off the shoulders, leaving a few stitches at the outer edge, then join the two shoulder seams.

Finishing: sleeves, crew neck and first wash

Pick up stitches around each armhole, including the gusset, and knit the sleeve downwards in the round, decreasing steadily to a plain cuff that measures about eight inches around. A ribbed cuff of two inches keeps its shape well.

For a simple crew neck, pick up stitches evenly around the neckline — roughly three stitches for every four rows — and work one and a half inches of two-by-two rib on smaller needles. Cast off loosely, or use a stretchy cast-off so the head goes through comfortably.

Finally, wash the jumper by hand in cool water with a wool detergent, rinse gently, and dry it flat on a towel, patting it into shape. Never hang a wet gansey. After that, wear it hard: it was designed for weather, and it will only improve.