The Duke is wearing a plain white shirt, which creates a strong contrast under a dark jacket. You can’t see his jeans in this photo, but they’re a solid colour, and a neat fit all round.
The Duchess is wearing a checked shirt, which is also popular amongst men these days… but again the look is strengthened by a dark jacket.
So as cooler weather approaches (here in the southern hemisphere), consider wearing a dark jacket with jeans and a shirt to create a look that’s strong, confident and relaxed. It's perfect for social occasions, dates, and informal business meetings.
If you prefer checked shirts consider a small check. It looks less casual and more serious than a trendy tablecloth-check, and from a distance it looks more like a solid colour. It's hard to see in the photo above, but the Duke's shirt is actually a small blue check.
If circumstances don't warrant a jacket, try to wear a solid coloured shirt to create a strong look.
And if it's a casual event or a hot day, rolling your sleeves up is not only cooler, it makes you look like a 'get stuck in and do some work' kind of guy... even if you're not doing any physical work on that particular occasion.
All in all, it's a right royal example of dressing simple, strong and functional,
with an obvious quality, and an understated elegance.
It's a Primal Thing.