In 2015, after the passing of his boyhood friend, Simon Marsh, Kaplan parted with the two Spitfire Mark I fighter planes that he and Marsh had as partners restored with Historic Flying of Duxford, Cambridgeshire. The first of the planes, Spitfire N3200, was gifted in the presence of Prince william, the Duke of Cambridge, to the Imperial War Museum at Duxford, where it had last flown as the personal aircraft of the Commander of 19 Squadron, Geoffrey Dalton Stephenson, later personal pilot to King George VI. The second, Spitfire P9374, flown by Captain Peter Cazenove over Dunkirk, was sold at auction at Christies London, where it achieved a record price for any spitfire at auction, the proceeds of which were donated for the benefit of the RAF Benevolent Society, Panthera, Oxford's WildCRU and Stop Ivory.