I am in a similar position, I graduated from uni in 2000 and got my first job within the BBC as a communications engineer, I stayed in this job until our outside broadcast commitment dried up.
I then moved onto news engineering in London, a dire, boring job which was made bearable by me doubling my shifts with overtime which netted me close to £75,000 PA, i should point out i was working 14 hours a day with 2 days off every three weeks, so would have probably killed myself if i'd done it for much longer. I then moved in Broadcast Control Systems my basic salary increased but I lost my overtime, but hey, the hours were exteremely flexible.
I've now been this position for 18 months and so far had no promotion or salary review even though I've taken more responsibilities and learnt plenty of new skills. Because the BBC is publicly funded they have to be very careful about where they're seen to be spending their money, so the typical over-inflated private sector IT salaries are nowhere to be found. This is good because it means no-one wants to take a severe paycut to do the same job, admittedly we've not come across anyone from outside the BBC who are any good anyway, the last two recruiment drives resulted in no new appointments.
I've resigned myself to the fact that if I stay in my current job I will never be earning the big bucks. But then again, I enjoy my job, i've travelled all over the world for different projects, and I'm on a permanent contract. The thought of being an IT contractor does not hold much interest for me.

Bottom line, if you still enjoy your job and there's no immediate job-security fears, then stay where you are. If you've really had enough then it's time to leave. I've managed to paint myself into a corner with my job, the only chances of employment outside my current job are 200 miles away down in London.