Where you work and in what industry also has an impact. When I was working in London I worked for a Greek shipping company (from University, for 5 years) then a magazine publishing company (for 4 years). I was pulling in pretty good money, especially since I was living with my parents and so had limited expenses! Definitely enough for me to put a 20,000 pound deposit on a house.

Then I joined an outsourcing company working in a bank in the City Of London. I got paid close to bank salary rates for a senior Unix SA/engineer (but without bonuses and benefits and stuff) and within 6 months my pay had increased by 50% (pay rise and promotion and thus also qualified for company car allowance or equivalent in money) over the previous job. The industry standard (City geeks) is that much higher than geeking in most other areas. If I worked directly for a bank then I could probably have been paid even more.

Having seen a lot of the programmers in this place, most of them ain't worth 30K :-)