'GS' (i) was the designation of Allied convoys (together with a numerical suffix) plying the route from Grimsby on the Humber estuary to Southend on the Thames estuary, and as such reciprocals of the 'SG' (i) series (March/April 1940).

Th first of the series was GS.1 of 6/7 March 1940 with unspecified ships, and the last was GS.32 of 13/14 April 1940 with seven unspecified ships.