I'd completely forgot about Rattletrap, I now remember reading about the car in VW Motoring during the eighties. The DVLA have the car down as a 1950, the museum doesn't have it SORNed either :d
The vehicle details for 10 BXK are:
Date of Liability 21 12 1994
Date of First Registration 02 03 1961
Year of Manufacture 1950
Cylinder Capacity (cc) 1192CC
CO2 Emissions Not Available
Fuel Type Petrol
Export Marker Not Applicable
Vehicle Status Unlicensed
Vehicle Colour BLACK
December 1966 UK 1500 Beetle