Outerwear is the only category where I have never regretted spending more, and I have thought about why. It is partly use: a coat gets worn every day for five months and nothing else in your wardrobe works that hard. But it is mostly that a coat is the silhouette. Everything underneath is a rumour.

It is also the category where the market is least honest with you, because a wool coat and a wool coat can be separated by a decade of life and look nearly identical on a rail.

So this is a practical piece rather than a philosophical one. Three groups below, and for each of them the things I would physically check before paying.

And one general note: try every coat on over a jumper. A coat that fits over a T-shirt in September is a coat you cannot wear in January.

Wool coats. Weight is the first signal and the hardest to fake. A proper winter coat has real mass in the hand; if it feels like a shirt, it will not hold a line and it will not hold heat. Look for melton, double-faced wool or a heavy twill.

Then read the composition. Wool with a small percentage of cashmere is softer and pills faster. Wool with polyamide or nylon is more durable and less lovely. Recycled wool is often shorter-fibre, which means more pilling, and that is a genuine trade rather than a scandal.

Check the lining across the shoulders and down the back. A full lining in a smooth fabric means the coat will slide over knitwear instead of dragging. A half lining is fine on a lighter coat and irritating on a heavy one.

Last, look at the shoulder. A dropped shoulder gives you room and reads relaxed. A set shoulder reads sharper and is much less forgiving of the wrong size.

Leather and suede age better than almost anything else, on one condition: you have to treat them like they are alive, because they are.

For leather, full-grain and top-grain are what you want, and the words matter. Genuine leather is a lower grade despite sounding like the highest. Look at the cut edges: a finished, painted edge is a sign of care in the make. Suede should feel dense rather than fuzzy, and it will mark, permanently, so a pale suede jacket is a commitment rather than a purchase.

Care is simple and non-optional. Brush suede after wear. Proof it before winter. Condition smooth leather once or twice a year and keep it off radiators. Never dry either one with heat.

Blazers are the third group because a good blazer does outerwear work three seasons out of four. The detail to check is the chest: press the front panel between your fingers and see if you can feel a separate floating layer. That is canvas, and it is why some blazers keep their shape for twenty years.