Just to give you an idea of how expensive it is, I share a house in a nice area of London. The rent is £1,500 a month¹ (almost $3,000 U.S.), but for this large of a house, that's actually a great price for the Ealing Broadway area of Ealing. I split that with Bob, another programmer here, and Doug (rabbleuk), someone who lives in Nottingham but commutes to London several days a week. People working in London but living in other cities is not unusual. It can often save you quite a bit of money. In fact, some folks let out a room for just a few days a week and have the place to themselves on the weekends when their housemates take the Eurostar back to their homes in France or Belgium.
On the plus side, if I can swing buying a house in London in the next year or so, because salaries are higher here than elsewhere in the UK, my relative earnings being poured into property means that come retirement time, I'll have a larger fund to show for it, thus allowing me to retire. There are several large, but nice European cities in which my money would go much further, particularly in Eastern Europe.
I also read in the paper today that some folks think they can solve the "high rent" problem by limiting the number of houses a landlord can own. Dumbasses. Don't they teach basic economics in school in the UK?
1. Don't forget that the £1,500/month rent is relative to local salaries. It's high and I wouldn't want to pay that on my own, but salaries tend to be higher as well. That's why it works out.