The State Earnings Related Pension Scheme (SERPS) was a top up to the state pension, benefiting those working and paying national insurance. It operated between 1978 and 2002 and was then replaced by the State Second Pension, now the single tier pensions – a flat rate state pension that is based on the level of National Insurance contributions over your lifetime.
If you ever contracted out of SERPS, you may have a substantial amount of money sitting in a pension plan that you’ve forgotten about.