A lot of the confusion comes from the DWP. If you ask them for a pension forecast with less than 10 years to retirement the answer is a firm 'No'. They direct you instead to the DWP online system that, once registered, will show you your NI record, any missing years and finally your current (how many years you have earned) and predicted (how many years you have to make-up the shortfall) state pension. Phew.
Except the answer it gives is wrong.
Inexplicably the online record does not take into account 'contracted out', well at least mine does not and I know I am not alone. It is entirely understandable that confusion reigns when you have a system will not give you a pension forecast until it is too late, whilst giving you online access to your own record which can be considerably in error.
This is a Government issue - they dictate my pay, pension, tax, NI, state pension forecast and online NI record. I have no control at all. I don't accept that I have received a discounted rate of NI either, or have put less into the NI pot. The removal of the NI cap on a % of our salary years ago means that higher earners pay considerably more NI than is otherwise required for a maximum state pension. As a case in point, my wife (contracted in) will receive more state pension benefits than I, but her annual NI bill is lower than mine.
Pay more, get less with a sprinkling of inaccurate forecasts.