Hermes Picotin Lock 18 CM Bag Handmade In Taurillon Clemence Leather Silver Hardware 7P Bleu De Prusse

There is navy, and then there is Bleu de Prusse – the colour of ink before it dries, dense and faintly green-black in shadow, unmistakably blue in daylight. It is the deep blue I recommend to people who own one blue bag and need it to work with everything. Blue it is, and blue it stays, whatever the season.

Eighteen centimetres across the front, thirteen deep, eighteen tall: the classic Picotin cube, made here in Taurillon Clemence, the pebbled, soft-handed bull leather. Silver-tone hardware suits Prussian blue almost chemically – the cool metal sharpens the deep tone instead of warming it – and the padlock tab stays the bag’s single flourish.

I carry a phone, a passport and a wallet, with keys tossed on top where I can find them. Because there is no interior lining or division, I keep a slim pouch for coins so they do not swim at the bottom, and I have never once had to dig around in it.

What to weigh: Prussian blue can pass for black at night, which some people love and others find sneaky – in lamplight only the hardware and the faintest green cast give it away. If you want one honest colour at all hours, choose a lighter blue; if you enjoy that trick of the light, nothing else in the range does it better.

One last thought: of all the navy bags I have carried, this is the one that has never once asked me to change an outfit to suit it. It simply comes along and behaves.