To the best of my knowledge the Regiment never used RR`s in the desert, so no "pink" ones. There are records of using them in urban theatres for counter -terrorism, I`ve seen photos of a couple with strengthened roof racks and adapted front bumpers, in both cases to mount ladders for access to buildings, but for obvious reasons its difficult to tell what they`ve done to the inside. I`d have been interested in how the dealer was going to prove the provenance of the vehicle, it won`t list anything remotely interesting under previous owners and I`d be amazed if it ever had a military registration for you to check back.
Have a look at Barry Davies` book on the illustrated history of the Regiment if you`re still interested - the chapter on counter-terrorism - there are photos on there of a couple of e platers