SERPS provided an earnings-related addition to the Basic State Pension paid by the Department for Work and Pensions (DWP).
SERPS additions were based on National Insurance contributions made between 1978 and 2002, with a maximum of 20 years' contributions counting.
Members of the LGPS were automatically contracted-out of SERPS for the duration of their LGPS membership, and for those new state pensioners reaching state pension age from April 2016 this has been taken account of in calculating their state pension.
This scheme replaced SERPS - see State Earnings Related Pension Scheme. S2P was a top-up to the basic state pension until April 2016 and members of the LGPS automatically contracted-out of S2P for the duration of their LGPS membership.