 Duncan was ordered under the 1930 Naval Estimates on 2 February 1931 from Portsmouth Dockyard . She was laid down on 25 September 1931 , launched on 7 July 1932 and finally commissioned into the Navy on 31 March 1933 . Built as a flotilla leader , she displaced 25 long tons more than the rest of her class and carried an extra 30 personnel . These personnel formed the staff of the Captain ( D ) of the flotilla . 
