SERPS, and created new private-sector personal pensions for many of them to opt into.

ECONOMIST: Tomorrow's pensioners

There is also a very useful factsheet produced by the Financial Services Authority entitled Contracting out of Serps.

BBC: Pensions questions answered

Serps was introduced in 1978 and since April 1988 it has been possible to opt out (known as contracting out) of Serps via a personal pension plan.

BBC: Pensions questions answered

The state pension comes in two parts, a basic state pension and an earnings related element previously called Serps, but now known as the State Second Pension (S2P).

BBC: Pensions questions answered

If someone elects to do so, rather than building up an entitlement in Serps instead the government as an incentive will pay a rebate to your pension provider, which they will invest on your behalf.

BBC: Pensions questions answered