Well will try to answer both of you in the one reply
Mark I can again assure you 148574 is not a Cabriolet–Vin 148594is the last Cabriolet built and was owned by JDHT until they had their clearcut a few years ago at Silverstone Auctions,
The early Cabriolets from Body number one were as you suggested used for testing etc the earliest to survive being Body # 005 but as Body numbers don’t run consecutively it was in fact the 9th car built & to date 25 years later on since I created the Data Base nothing earlier has shown up/
The cars used by Tickford in designing the Cabriolet were old stock V 12’s Coupes with rear seats & safety belts.