PRESERVED FORCES PENSIONS
If you left the forces before April 1975 and unless you had served 22 years, you were not entitled to receive a pension.
These rules were changed in April 1975 so that if you left the service after that date and had served for at least five years and were over the age of 25, you became entitled to an inflation proof pension payable when you reached the age of 60, plus a terminal grant of 3 times the annual pension. Those with 12 years service received a pension of over £300 a month plus about £12,000 terminal grant.
I personally missed that date by about 18 months and I have heard of those who missed it by a few days. Indeed there were many servicemen who would have qualified for a pension but were "encouraged" by the MoD to end their service early, by a matter of a few months, without being made aware of the impending rule changes. The MoD obviously wanted to avoid paying the pensions.
There are currently two groups lobbying to have the rules applied to all those who ended their service prior to April 1975. These are Combined Armed Forces Federation UK www.caffuk.org.uk and Armed Forces Pension Group www.afpg.info
If you left the service prior to 1975 without receiving a pension I would urge you to take a look at these websites and perhaps sign up to their campaign, it will cost you less than £40 per year and if their fight on your behalf is successful then you may receive a lot more than that in return.