You can tell a lot about a designer by the way they approach the design of a classic black jacket. And you can tell a lot about a person by the classic black jacket they choose to wear.

And so I find myself, dressing for a reasonably (and unusually) formal occasion, one that requires smartness, but not outright fashion ferocity, doing an early morning twirl for my other half who, while visibly pained, will hopefully help me find the right balance between the two.

"You look too thin," he says, when I try on a Balenciaga jacket, an outrageous slur and, on any other occasion, a very good reason to wear the garment in question if only out of spite. It's all in the signature high-cut arm holes and ultra skinny sleeves, incidentally, and no more true a reflection of the body inside it than the oversized jacket of a Zoot suit, say, might be.

Next: a Chanel, bouclé wool jacket complete with metal chain in the hem to ensure it hangs just so. "You look normal," says the in-house fashion jury, which is meant as a positive but it doesn't feel that way to me. Neither, come to think of it, would Chanel be overly impressed. Since its inception, this design was always intended as relaxed, but "maybe lose the word normal," I tell him. Effortlessly chic, perhaps?

Moving on and a much-worn and loved Yohji Yamamoto jacket gets short shrift: it has a deliberately shrunken, poor-boy feel and deliberately shrunken, poor-boy is not the order of this particular day.

Strong-shouldered McQueen? "That's a brilliant jacket, but it's the sartorial equivalent of telling someone to f*** off," apparently.

And so I reach, perhaps inevitably, for a lightweight wool Jil Sander jacket [pictured] which is, if I have to say so myself, the height of elegance – nice but in no way boring. As always, the devil is in the detail. The waist is higher than is usual, forming a discretely feminine line; the sleeves are generous, so the overall effect is easy, not uptight; the shoulders are slender, as opposed to power-crazed, but quietly assertive nonetheless. As for the fabric, suffice it to say that I might even be able to curl up for a cheeky afternoon nap in the fashion cupboard in it from where it will emerge miraculously unscathed.