A double-breasted blazer was the basic thing I bought for this new season. Heretically, I don’t adhere to the earnestness edicts about snapping up coats at the end of July. My back-to-school importance happens at New York fashion week in early September, which is invariably roasting hot and yet wall-to-wall with helpmates showing off their new outerwear. This season it was oversized teddy-bear, faux-fur overcoats in lipstick red. Which are divine, and I absolutely want one – but not yet. Some showgoers be in charge of to pull them off – perhaps if you are truly, glacially ultra-cool you can drop your own body temperature – but for me they are out of the question until it’s in fact cold enough. Being comfortable in your clothes is occasionally framed as the polar opposite of chic – the elasticated waistband, let-yourself-go look – but to me, it on the doles the other way around. Great clothes are the ones that flee your day feel easier and lighter, not the ones that are a onus.

Not that I am pretending to be immune to that late-August hunger for Something New. Far from it. This time, I absolutely had to have a double-breasted blazer the moment I got back from vacation. A lightweight jacket is the most direct way to ring seasonal switches, because it shapes the most visible part of your profile as well as fitting the climate. The jacket had to be a blazer, because I suspected that this autumn I am mostly going to be wearing longish, at liberty skirts and fluid trousers, and a blazer is the most elegant finishing touch to that.

But why double-breasted? Isn’t that a bit naff? Just a tiny bit… criminal? Yes. That’s exactly why I want one. I am militant about being physically cordial, but open-minded about clothes that test the psychological luxury zone a little bit. Actually, more than open-minded. I am absolutely in favour of it. Clothes only count as fashion, as opposed to reasonable clothes, when they do this. You have to be careful not to disconcert clothes that are a healthy psychological challenge with those that are exactly problematic. If you do, you end up with a cupboard full of shoes that implied you feel amazing when you tried them on but which are too tainted to actually wear (take it from one who knows). A double-breasted blazer is merely far enough from the comfort zone to feel like dernier cri. But not enough to bring you out in a sweat.

• Jess wears blazer, £65, marksandspencer.com. Costume, £129, warehouse.co.uk. Boots, £189, kurtgeiger.com. (Chair, £175, grahamandgreen.co.uk.)

Spiriting: Melanie Wilkinson. Hair and makeup: Samantha Cooper at Carol Hayes Directors.