Could this be the Mini Jem prototype?

I recently came across this shoddy picture of a Mini Jem brochure. It features a Mini Jem Mk1, and a very early one it seems too. In fact I believe it has to be the earliest Jem in a brochure or leaflet, and perhaps this could be the prototype. The London address of Jem Developments that it states is the place where Jeremy Delmar-Morgan built his first few cars. There is another Mk1 brochure (see here, also for the Mk2 and Mk3 brochures) but that shows the address where production moved to in November 1966 and so the one featured here has to be older. Could the car shown on the pictures (registration KGH856C?) indeed be the prototype? Who knows more? Or who has a copy of this cool brochure?

Other then known brochures, this leaflet shows original address in London where 

Mini Jem was born. Could the car be the prototype? Also note delicious works Transit Van 

UPDATE 25 May: Richard Porter wrote: "Jem no. 5 is KGH 858D - could it be that one?" I think he is right - I'd totally forgotten about its registration number while that particular car was fully featured in 'Maximum Mini'