'A racing stripe looks brilliant when seen from knee-to-ankle under a trenchcoat'
There is method in the madness of fashion. Or maybe it's closer to the truth to say there's madness in the method, but let's not split hairs. The point is that even when fashion seems away with the fairies, there will be – somewhere – a silk thread of connection to the real world of getting-dressed-in-the-morning. Gossamer-thin and dry-clean only that silk thread may be, but it's there.
And so we come to trousers with a go-faster stripe, or racing stripe, down the outside hem. They will not, let's be clear, make you go faster. This is because, unless you want to look like a clown, you need to wear them with heels. Nonetheless, the go-faster trouser is the new It-pant, knocking the formidable cocktail trouser from the long-held number one spot.
While they may not live up to the utilitarian claim staked by their name, the go-faster stripe trouser is a more practical all-day trouser than the cocktail variety. A brightly printed trouser looks better with a waist or jacket than with a longer coat. Put a coat over a print trouser and you veer into pyjamas-and-dressing-gown territory. You can overcome this, as they do on the catwalk, with hours in hair and make-up, and a couple of grand's worth of status leather goods. But that's not always practical before work. A racing stripe, on the other hand, looks brilliant when seen from knee-to-ankle under a trenchcoat.
The racing stripe is part sportswear (think old-school tracksuits) and part tuxedo dressing (a traditional tuxedo, or le smoking, has a grosgrain or satin ribbon running down the outside leg.) It also looks a bit like the old packets of Wrigley's Spearmint gum, with that bold straight arrow. So you get a bit of dynamism and a bit of formality, and a blast of minty freshness. It's not a cuddly look. Where conversational prints function as an icebreaker – "Are those owls on your blouse? I love owls!" "Me too!" – a stark single stripe is the opposite. It suggests a cool self-possession, a simple document-folder day clutch, and a schedule that doesn't permit hanging around to chat. It's very Céline. You might not be able to stride out in those heels, but the trousers will do the swagger for you. Method in the madness, right?
• Jess wears trousers, £175, by Karl, from net-a-porter.com. Leather top, £199, Marks & Spencer, marksandspencer.com. Shoes, £39.99, Zara, zara.com.
Styling: Melanie Wilkinson. Hair and makeup: Dani Richardson at danirichardson.co.uk using Mac Cosmetics.