These are the rules for AFPS 75:
If you die
in service your spouse would get a lump sum of 3 times your pay, a pension equal to your pay for 91 days (182 days if there are eligible children) and a pension normally worth 50% of the pension you had built up to the date of death.
If you die after you have left service with a pension your spouse would get a pension equal to your pension for 91 days (182 days if there are eligible children) and a pension normally worth 50% of your pension thereafter.
For completeness, if you die having left service with a preserved pension, your spouse would get your preserved lump sum and a pension normally worth 50% of your preserved pension.
The 'normally' is there because there are differences for those who have service before 1973 (when widow's pensions went from 1/3 of the member's pension to 1/2) or 1978 (prior to which women who married ex-servicemen were not entitled to a pension on his death), and, of course, divorce can have alter benefits in line with the judge's ruling.
This pension ceases if the recipient remarries or cohabits. The Forces Pension Society (
Forces Pension Society - Fighting for the Forces and their Families) is currently campaigning to have this rule abolished in the same way as the Northern Ireland Assembly has abolished it for widows of members of the RUC.