ricardian,
Reference your:
"I later found that I could not even count that 12 yrs RAF service towards my Civil Service pension after 30 years service as a Radio Office with GCHQ".
I had the mirror image of that problem. My last employment was with HMC&E, I did 13½ years, which made me pensionable. But then I'd done 11 years ('38-'49) before with the Civil Service (they included war service, the idea was that you were only a civilian nobly doing your duty for King and Country).
If I could have tacked that on, I would have got 24½/80 of my final salary as pension, instead of the 13.5/80 I actually got; it would have made a difference over the 29 years I've been retired from C&E.
"No", they said, "you burned your boats when you resigned in '49, we told you so at the time, now go away". Ah, well....
Cheers, Danny.