What's with the deconstructed winterwear?
Yes, fingerless gloves, peep-toe boots and now sleeveless coats. Technically, we could call this boiled grey wool number from Hobbs a waistcoat, as they do (£199, available mid-October, hobbs.co.uk, above), but that just reminds us of far less stylish, ill-fitting men's wedding attire.
Still not sure I see the merit of a sleeveless coat.
Well, beyond the fact that it's fashion, stupid, this is a good in-between-y garment. In between seasons, when you don't need maximal thermal protection; in between environments, when you're skipping between overheated shops and cold streets.
And the aesthetic?
A sleeveless number is nice for really integrating your outfit rather than just hiding it with a big coat (admittedly the latter is often a blessing on the less artful days). This way everyone can feel the benefit of that great knitwear you're sporting.
If it's not a waistcoat, is it a gilet?
The gilet is a close cousin and there are plenty of those around this autumn too. Compared with the long, clean lines of the sleeveless coat, gilets are more of a squashy, textural choice – Maison Scotch's teddy-bear wool (£155, asos.com) is a cosy but not-too-voluminous option.