So far, I have done the following searches based on the advice here and on other forums.
MOD FoI request - nothing as it was pre-MERLIN
RAF Museum - pointed me at the forums as a possible source of help
RAF - still waiting
Heritage Museum, Gaydon - Heritage Certificate purchased, found out the colour and build date and first 'home'
RLC Archive - card in the big 500k pile - next chassis along was in service in July 1973 and ended up with RAF.
So, I am hoping that somebody might, just might be able to help me find the military number plate that was attached to chassis no. 951-01236A or its current civvy plate UCU971Y. It seems that the military number is the 'keys to the kingdom' with regards to information.
UPDATE ---
Turns out the original colour was RAF Blue Grey. Build date was 18th May 1973. Despatch date was 25th May 1973. Its destination was Central Army Vehicle Depot, Ashchurch. Label (line) number 3/786??
I guess, its time for the moths to again be released in order to elicit that elusive military number!
Thanks to those who have added to my understanding so far. Its a really interesting thing to research. For any piece of info I've found, I've uncovered a host of 'side' information that is also really interesting.