Ian I have a couple of examples of genuine markings, seen on Rover 11 Ambulances in 1980s.
30 FJ 20 (used to own this one) SE/223 on nearside wing, was attached to Shorncliffe Barracks, Dover. Don't worry about stealing its identity, it now masquerades as having served in N.Ireland & has assumed a new 'history' :shake:
07 FL 46, saw this at an official Bovington event, LOND/74 on offside wing
Relatively few vehicles were marked up but at least those are identities that were real.