Fort Blockhouse was originally the site of a coastal tower built in 1552. In 1824 the sea facing battery was upgraded to a casemated battery with thirteen emplacements. Further extensions and improvement were made in 1845 and 1863.
By 1859 (Royal Commission) the armament of the Fort was fifteen 36-pdr and fifteen 18-pdr SB guns.
1872 returns show the armament to be six 7-inch RBL guns, fifteen 8-inch SB and nine 18-pdr SB.
By 1900 the armament was five 12-pdr QF guns and two Maxim machine guns primarily to combat Motor Torpedo Boats
Fort Blockhouse remains under the control of the Ministry of Defence (2022).