What actually happened to cause the Caudron to crash has never been fully explained; some hypothesised that the aircraft suffered structural failure, since a wing was found in an adjoining field. Engine failure was also suggested as a possible cause of the crash. Watson's RNAS casualty card offers no clues, merely stating the time and place he was killed. Buried on 5 July 1915 in Dundee's Western Cemetery, he was survived by a widow and two young children. What became of his aeroplanes and his research is not known.