Tracing the history is a work in progress, thanks to the Royal Logistics Corps Archive we have the MOD record card which seems to show a very uneventful life at either RAF Coltishall or RAF Wittering from 1989-2001, seemingly going direct from BCA to Witham Specialist Vehicles to Chris, the first civvy owner who kept it for many years.
The Merlin 2.0 Document released under FOI shows it's one of 44 units supplied, quite a few were supplied white, whereas Alfie is NATO Green IRR (infra-red reflecting). There's a website where you can search the Merlin archive which is really cool.
The record card shows the ambulance at RAF Coltishall, whereas the Merlin document shows it going on to RAF Wittering in September 1989
There is a group dedicated to preserving the memory of RAF Coltishall, http://www.spiritofcoltishall.com/.