The guns armed the following warships :
The gun was succeeded in the "heavy" 4-inch class on new warships commissioned from 1914 onwards by the QF 4 inch Mk V. This new generation of warships were more heavily armed, and the BL Mk VII's role as secondary armament on capital ships and primary armament on cruisers was taken over by the BL 6 inch Mk VII and BL 6 inch Mk XII while the 4-inch calibre became the secondary armament on cruisers and primary armament on destroyers.
In World War II many guns were used to arm merchant ships.
A battery of 4 guns mounted on field carriages was first deployed with the South African Heavy Artillery in the German South West Africa campaign in 1915 and returned to England in September. They were then deployed in the East African Campaign from February 1916 with 11th Heavy Battery (renumbered 15th Battery from April 1916) manned by the Royal Marine Artillery.