"population in work (25M ish) and that we remain the fourth largest economy in the world after USA, China, Germany and ahead of France etc. etc."
Ahem. Japan? Economy 2-3 times bigger than UK. Also see:
Britain's economy overtaken by France, new figures show - Telegraph
We're basically a pissant little island off Europe with delusions of great power status and military adequacy waaaaay beyond our meagre capabilities. Don't forget that in PPP terms we're some way behind India and probably a few other countries too.