My husband died young. He paid graduated NI contributions and then SERPS until age 28 when he joined a company which has a very good pension scheme so opted out of SERPS.
I reached SP age in 2021. I worked and paid full NIC for over 35 years so I receive full SP in my own right, but I also get a small amount of inherited pension based on his graduated contributions and SERPS.
The inherited pension would, of course, have been greater has he remained in SERPS (and the second pension scheme which superceded that) but by opting out, he enhanced his occupational pension of which I inherited 50%.
Without going back through ancient records, I can't say how much his occupational pension was enhanced by the SERPs opt-out but I know I have been better off financially for him having done this. I have had my occupational widows pension for going on 20 years whereas I only received the inherited SP from age 66.