The DB2 appeared in April 1950, and the DB2/4 in 1953. I'm pretty sure that the car is a rebodied pre-war model, and the owner was trying to update its appearance with a barchetta-style clothing. It doesn't look stylish enough IMO to be the work of a known coachbuilder.
(PS when I say pre-war model, I mean a catalogued model from before WW2, but still available for sale in 1949)