Regulation D20 National insurance
Subject to paragraph (2), where a pension is payable to a member who attains state pensionable age in respect of a period of service in a non-participating employment, which counts for the purpose of calculating any benefits payable to the member (other than excepted service), no provision in these regulations—
for the surrender or assignment of a pension, or
for the reduction, termination or suspension of a pension,
shall apply so as to reduce the pension below the minimum rate of equivalent pension benefits applicable in respect of that period of service under the Insurance Acts.
Paragraph (1) does not apply to any provision for the reduction, termination or suspension of a pension, which is used for a purpose prescribed by regulations made, or deemed to have been made, under section 57(1)(c) of the National Insurance Act 1965 (equivalent pension benefits).
For the purposes of paragraph (1) “excepted service”, in relation to any person, means any earlier period of such service as there mentioned, being service in respect of which—
a payment in lieu of contributions has been made, or
equivalent pension benefits satisfying the requirements of the Insurance Acts have already been assured to him.