If you have been a member of a salary-related pension for more than two years, you are entitled to a deferred (or 'preserved') pension. This will be paid to you at the scheme's normal retirement age, though you may be able to ask for it to be paid early.
The amount you get will depend on the pensionable salary you were getting when you left the job, your length of service and the scheme's accrual rate – just as if you were retiring.
The pension is then uprated (or 'revalued') for each year you defer it, to take some account of inflation. The way this is done is very complicated as it depends partly on scheme rules and partly on government legislation, which has changed several times.
As an alternative to leaving your money in your old employer's scheme, you may be able to transfer it to your new employer's scheme. This is covered by the next few questions.