I think you will find that Generals retire on a pension of approx half pay (Depends upon which pension he was on and how long he served etc, etc. Field Marshalls used to stay on the active list and receive full pay, I think, but the rank, along with Marshall of the Royal Air Force and Admiral of the Fleet, was deemed unnecessary some years ago.
Try this;
http://83.138.137.164080/WizPersonalDetails.aspx
Phil.