Binic Breton sweater, £199, Saint James

Of course, Prince William certainly doesn’t have to take lessons in dressing well. While his taste might err on the casual side, the heir to the British throne comes from a long line of men in the Windsor family who are rightly regarded as models of elegance. They know how to promote the British style envied and copied throughout the world. It’s a form of sartorial excellence known to the best-dressed French men, who don’t hesitate to cross the Channel to have perfect suits made, whether in days gone by at Henry Poole – Emperor Napoleon III’s official tailor – or today with Jeremy Hackett at 14 Savile Row.

But just as we French have taken inspiration from British tailoring, so British men, like Prince William, might find some style pointers in our style instincts. Here’s my advice for him…

Take a relaxed approach to tailoring

When it comes to elegant casualness, French fashion houses are beginning to explore some interesting avenues. With an innate knack for tailored nous combined with an effortless knowhow for modern streetwear, Parisians know how to combine the two. The French style finds its sophistication in a sense of restraint. Simple, minimalist cuts, lean proportions, a muted colour palette. It’s all about getting to the point. No overly conspicuous dandyism. But made with beautiful materials – see the cotton and silk blend of a Cifonelli jacket for example – and the finishes meticulous. 

Have fewer but better clothes

As Gauthier Borsarello, creative director of Paris brand Fursac, and fashion director of L’étiquette magazine, says: “Strict, demanding, and sometimes austere, the purest Parisian style requires having few clothes but all of high quality, wearing them a lot and with nonchalance.” 

The one piece which will work hardest in your wardrobe

The navy blue blazer is undoubtedly a pillar of the classic French style for men. Ideal for the office, a family celebration or at the weekend with a pair of jeans or chinos, it’s a daily basic that any gentleman from Saint-Germain to Saint-James can find in the affordable collections of French brands such as Officine Générale, Octobre Editions, Breuer, Fursac or Crémieux.