A long coat is the one purchase worth making before the weather demands it, for the straightforward reason that full size runs exist in September and not in December. It is also the piece where the money is most visible, since a coat is worn over everything for months and is the first thing anyone sees. The composition tab is where to start. A high wool content, ideally above seventy per cent, will hold its shape, resist wind and last many seasons. Wool blended with polyester below about fifty per cent starts to pill and looks flat within two winters. Cashmere blends feel wonderful and are less durable than pure wool for a coat that gets worn daily, which makes them a second coat rather than a first one.

Length is a warmth decision as much as an aesthetic one, and a coat covering the knee is dramatically warmer than one ending at the hip because it protects the legs. Below mid calf becomes cumbersome on public transport and picks up dirt at the hem. On construction, a full lining in a smooth fabric is essential, since it lets the coat slide over a jacket rather than dragging, and an unlined or half lined coat will fight every knit underneath. Look for a vent at the back if the coat is long, or it will pull when you walk. Sizing should be done wearing a jumper and ideally a blazer, checking the shoulder seam still sits at the shoulder and that the sleeve is not tight at the upper arm.

Our approach is to buy one coat properly rather than two adequately, in a plain colour, at knee length or just below, with a high wool content and a full lining. That coat then does not need replacing for years, which is what makes the higher price rational. Camel and grey read softer than black and hide less, so a mid grey or navy is the practical middle. It is worth having the sleeves shortened if they run long, since a coat sleeve past the knuckle is the detail that makes an expensive coat look borrowed. If you take one thing away, check the wool percentage before anything else, because it predicts how the coat will look in its third winter.