Please may I try (again) to clear up one myth regarding Final Salary pension schemes.
I can only talk about the public sector because that's all I know about. If you are a member of the NHS pension scheme you CANNOT draw your pension until you reach pensionable age (currently 60 for females and 65 for males). If you 'retire' earlier, you have to wait until you reach that pensionable age but your pension will be calculated on years of service and salary at the time you 'retired' and frozen at that point in time.
The exception to this is the age at which nurses can retire and get their pensions immediately. This is, I think, 55 and recognises that many nurses suffer from back problems as they get older. I think GPs can retire earlier too.
Coincidentally NHS pensions have changed for new entrants and are based average pay than final pay plus, of course, length of service.
If you are an NHS worker about to retire now with a final salary of £20K and 20 years service, your pension will be about £5K a year. Sadly, many NHS workers earn less than £20K, and can't afford to join the pension scheme anyway (because it's contributory at a rate of, I think, 6% of salary).
I don't know anything about private sector pension schemes at all - final salary contributory ones that is. Perhaps someone could enlighten me?