I think that would depend on whether it was what is now described as a Final Salary Scheme. Historically, from the Army discharge record of my 2XGGF who was invalided out of the army in 1810, and the creative accountancy applied to his length of service with various units, e.g. joining before a unit was formed, and continuing in the unit 2 years after the muster roll shows he had left etc. it looks as though his record was massaged to ensure he had completed 10 years service, which I suspect though so far have not proved was needed to qualify for a pension.