Whoever decided less is more clearly hadn’t considered the jacket. Not to knock single-breasted blazers, but in the being-the-best-dressed-man-in-the-room stakes, two breasts are definitely better than one.

At least, they are now. The double-breasted jacket has served its time in timeout, the smell of power dressing bankers finally scrubbed off. The new DB is for the city, not The City. Which means less structure, slimmer shapes, and any colour and pattern so long as it’s not pinstripe.

There’s even – shock horror – a double-breasted jacket you can deploy when it’s sweltering. A way to wear more fabric and yet be cooler in every single sense of the word. This season, along with shedding its fustiness, the DB has also ditched its padding for soft-shouldered, incredibly Italian takes that feel more like a fancy cardigan than something to wear on Wall Street. “An unlined jacket with a soft shoulder is far less restricting in warmer climes,” says Giles Farnham, head of River Island Style Studio.

When you need something that keeps its shape, and your cool, fabric blends are in. Whether it’s wool and cashmere, cotton and linen, or some space age polymer with a hint of silk, by doubling up you get that all-important drape and lustre, without the sheen spreading to your face. “You don’t want a fabric which is going to be too warm or bulky, as the double-breasted blazer is best worn buttoned up,” says Ollie Arnold, style director at Mr Porter. On which note, first fasten the anchor button – that’s the one inside – then the middle button. Then find something else to do with your hands.

Not that buttoned up means, well, buttoned up. Worn right, the new DB is a utility piece that dresses down even better than up. “The key mistake people make with a utility double-breasted jacket is wearing formal underpinnings,” says Arnold. Your dad combined his with spread collars and tie knots the size of a baby’s fist. But yours looks best with soft button-downs, knitted ties, fine-gauge roll necks, even a round-necked Breton shirt.