Hi Grifterkid
I can't find the car your referring to - have you got an Ebay ID No? I guess the auction might have finished in the meantime.
#XC registration's did indeed encompass most factory cars. The reason is that this is the registration letters allocated to the Solihull Road Tax office at the time. So all other cars registered in Solihull area have this reg as well, including, of course, many Rover's sold direct ot the public.
Rover's registered a surprisingly large number of cars as factory cars. As well as the sexy experimental cars and press demonstrators this included all the cars given to managers, foremen etc etc as company cars. The whole industry used this route as a safety valve to absorb production at slack sales times of the year, and the cars might well be sold on after as little as 4 to 6 months.
Bottom line is that to determine whether or not it is of interest, first clue is to look at the spec, second is to take a trip to Gaydon to inspect the factory Register, where they are all listed (except that one year is missing (1965?)) with what purpose they served, who they were allocated to etc etc.
Regards
Chris