Mr Williams was out and about in New York recently, performing at NBC's Today show Toyota concert series and he looked absolutely smashing, as per – his stone-wash number is great and so versatile. If you're still after a jacket that looks boss wrapped around your waist but will keep you warm when the sun goes down at the festival/park/pub, then you need to get involved with some washed-out denim. Match it with a white graphic-print T-shirt or vest, or smarten things up with a shirt and chinos.
It's also worth noting that Williams has retired his big hat and gone for a pleasantly dishevelled fedora. They're an easy win on the beach and will actually keep the sun off, too.