I agree he looks nice maybe for a night on the town or golf at the club. He is a nice looking young man.
Maybe if everyone else was dressed more casual too like his wife in a sundress and his son in a pair of shorts instead of a gown but that isn't what I'm picking up on here even by his brother. Even the other mens coats are closed for the official family photo, it doesn't seem to be a semi casual suit event for the men or woman.
I did note that Princess Diana's sisters didn't arrive in casual dresses either. Maybe he took it down a few notches cause Queen Mum declined to attend?