The J class was designed by the Royal Navy in response to reported German submarines with surface speeds over 18 knots (33 km/h; 21 mph).

[1] The conning tower on J7 was sited 60 feet (18 m) further back than her sister boats, as the control room was located behind the machinery spaces.

[3] After the war, the British Admiralty decided that the best way to protect the Pacific region was with a force of submarines and cruisers.

[1] By the time J7 was returned to service in June 1922, the cost of maintaining the boats and deteriorating economic conditions saw the six submarines decommissioned and marked for disposal.

[4] Some years later a stone marina was constructed around the wreck, which was left in situ and visible, being too expensive to remove, where it continues to deteriorate.