Yes it was a wild shot, more to determine the country of origin than determine the base. However, I figured that if it was British, and small, that I might as well try a very popular small car from the assumed time period (50's - 60's). Sometimes one just gets lucky, I guess.
I'm not sure my luck will hold out though, as there appears to be very little information about this vehicle on the internet, which is my only source of information. I was able to discover the designer/builder (now deceased), but I haven't been able to locate a name (if there is/was one), date/model of the base, or date of construction.
Based on what little I have been able to find, the puzzle car is a: "utility vehicle prototype", based on a Morris Minor, which was designed and built by Vic Roberts.