Firstly, I have loved reading this thread! Very funny.
Secondly, being a UK native I would love to wholeheartedly agree with the original statement. However I can't in good conscience. Most of the UK has a very relaxed attitude to what they wear in their day to day lives, with most people opting for a t-shirt with jeans.
There was a time when night clubs and even some bars had a strict dress code; no jeans, no running shoes, or sports apparel of any kind, but now even those have relaxed their dress code. The result is a multidute of overly fake tanned guys with greasy hair who look like the belong more on Jersey Shore than in a nightclub in the UK. (in fact google geordie shore (oh god the shame of it all))
Thankfully there are still those of us, (myself included) who wouldn't dream about leaving the house before making sure that even a casual look of jeans, t-shirt and trainers aren't perfectly matching and colour coordinated with our underwear. Or going for a night out without wearing a perfectly matching and pressed dress shirt, trousers (not pants boys and girls, they go under your trousers! Lol) with leather brogues and a matching well tailored pea jacket from Banana Republic!!!