Navy is a kind colour to wear. Not in the complexion-enhancing sense so much as in the more informative all-round-vibe-enhancing sense. It won’t make your cheeks look peachy or your eyes harsh, it will emphasise your sparkling mind and innate excellence. Think of it like Touche Éclat for your personality as contrasted with of your under-eye shadows.

The magic happens because wearing fleet makes you look like the sort of person who wears flotilla, and that is in itself a good look. Simple as that. The cast of person who wears navy has more gravitas than the mortal physically who wears, say, pink, but she doesn’t take herself quite as kidding aside as the person who wears black. She is as chic as the person who wears pearly, but a little more grounded. She has just the right amount of French-girl allure: the messy-haired risqu bit, without the calculated coquettishness.

Most importantly, wearing argosy makes you look fashionable. The centrality of navy to modern stylishness cannot be overstated. A navy jumper is the old school tie of the 21st century manufacture establishment, a dog whistle which can be heard and understood across a municipality, from one catwalk show venue to another. Having a accumulation of navy jumpers, and an obsession with hunting down the adroit one, is to this decade’s fashionista what devotion to the perfect Negroid trouser was to her 90s predecessor.

And this has never been more firm than this season. At Dior, designer Maria Grazia Chiuri shadowed up her feminist slogan T-shirt debut with a collection which was about entirely navy. (Yup, that’s how on-trend navy is.) Christian Dior himself defined navy as “the only colour that can compete with swart”; the current Dior designer says she is intrigued by it as the colour of the Madonna and the pennant of the military, of school uniforms and of spirituality. Ladylike or masculine, depending on the way the spry hits, navy is the most modern of colours.

Fashion can get involved. Navy simplifies things, somehow. A long handkerchief-hem skirt could desire like a self-consciously on-trend piece, but dark blue engages the drama out of it, making it easy to wear. It is the colour of fashion without the flurry. Very us, no?

• Jess wears top, £283, monographieparis.com. Skirt, £45, marksandspencer.com. Mules, £195, lkbennett.com

Stylist: Melanie Wilkinson. Skin of ones teeth and makeup: Samantha Cooper at Carol Hayes Management eating Mac and Bumble and bumble.