Hello,
Preserved pensions for the armed forces were only introduced on 31st March 1975. Only personnel serving on or after that date with 5 years or more reckonable service and over the age of 26 at that date could qualify.
Before this change service personnel had to complete 22 years regular service to qualify for a pension.
The answer is therefore unfortunately no, his wife would only have received a pension if the man in question died during service not once he had left the army.
I hope this is helpful.