Right on - London vs. US is very different. I envied my UK friends who left work at 4pm on Fridays to have a drink with their colleagues, when I'd regularly be working till 8 or 9pm.
I currently work in finance in London and have experienced very different! I was nervous, expecting to be working with MIT gods who would make me feel like an embarrassment of a human being. The reality is I am working with borderline retards from Utah who do no work whatsoever and when I explain in detail, they don't listen one bit. I'm the one left working 50-60hours to cover their lack of work.