Time was when shopping for a coat – newly, and in this case appropriately, re-branded outerwear – was simple. One waterproof. One wool and tailored. And, perhaps, a puffa for those who didn't mind looking like the Michelin Man. Now, as with all formerly strict dress codes, the boundaries are blurring.

The waterproof variety was always the easiest. There's nothing as fashion-police proof as the trench coat, which is simple, chic and (unusually) entirely practical. Now, though, it comes in many, often not entirely waterproof or indeed particularly practical, incarnations – leather, rabbit fur, taffeta and so forth. The simplest and most effective is still the original gabardine variety, but even that is nipped and tucked season after season to ensure that those who care about things will be encouraged to buy another one, not to put too fine a point on it.

The tailored wool coat, once a tad uptight, was more tricky. This, too, is the case no longer. Cocoon-shaped, dressing-gown inspired, or even in the form of an oversized jacket (Yves Saint Laurent ones are lovely), today's use of innovative yarns means that not only is there far more to choose from in terms of silhouette but also even the warmest choice is as light as a feather.

Enter, also, the chunky knit cardigan – sorry, statement knit – a more relaxed and less dressed up/obviously work-friendly alternative which looks particularly fine with the relentlessly skinny trouser leg that continues to dominate. Beware, though, the shedding of the most fashionable mohair/angora/alpaca design, which plays havoc with the black/white/grey basic worn beneath it. Hairy breasts are rarely modish.

This brings us to the puffa, formerly only for wear on the most bitter weekend excursions and about as aesthetically pleasing as bed socks. Yummy mummies have long favoured the North Face. And why not? It's warm – there's no arguing with that. Even yummier mummies opt for Moncler – high shine and in purposefully look-at-me colours. Uniqlo have a fine line in lower-priced down jackets although they're not quite downy enough to wear in the snow. Quite the most fashionable puffa to see and be seen wearing, however, comes courtesy of Junya Watanabe who, with customary finesse and technical brilliance, has transformed this formerly ungainly garment into an object of beauty. Watanabe has long loved a puffa but this season he dedicated almost his entire collection to it. Floor-length and mimicking the line of everything from a ball-gown to a sweeping cape, shorter and as elegant as an Edwardian walking jacket, twisted, folded and tucked around the body in a manner that few would – or, for that matter, could – ever rival, in this designer's hands even this, the most utilitarian of all outerwear, has a dignity and romance to it that is second to none.