I have a hazy memory of a circa-1990 fad in British menswear, which was also a thing in Japan at the time (perhaps where the Brits' inspiration came from) for wearing a shirt with no tie, and the top button done up (rather like some of the early images of Peter Capaldi as Doctor Who). Punch magazine at the time even did a cartoon with a posh restaurant that had the sign "Top Buttons must be Fastened" as a parody. It didn't last, though it has come back around in recent years on both television and politicians. I will find it a great shame if the tie does die - it's not much in menswear that is so gloriously, flamboyantly un-utilitarian, there solely for decoration. I would agree that the pocket square is rarer in the UK than the US... and does indeed look to have been so going back. It's more of a dandified - and I suppose perhaps an upper class - affectation. I wouldn't dream of going out without one in my jacket but certainly it's no more a historical 'norm' in the UK than, say, the spearpoint shirt collar that is so ubiquitous at vintage themed events. I hear you on everything save the jeans with the blazer..... when I was in my early twenties, I did that a lot, and I like to think I pulled it off with a Keith Richardsesque swagger. Now I'm fat and middle aged, it's a look that can be too Jeremy Clarkson for comfort. You're bang on about tucking the shirt, though. I don't like an untucked shirt at the best of times, but there's something downright absurd about one with a suit. Always makes me think the wearer is trying too hard to rebel - like the kids who wore their shirt untucked with their school uniform.