By World War I the class had either been sold, converted to submarine depot ships or minesweepers, or reduced to harbour service.

Three of the class were lost during World War I while serving in the minesweeping role.

This layout produced 3,500 indicated horsepower (2,600 kW), giving them a speed of 18.7 knots (34.6 km/h; 21.5 mph) with forced draught.

Speedy was a three-funnelled vessel (compared to the two-funnelled Admiralty design), but the key difference was the use of water-tube boilers instead of locomotive-type boilers; she produced at least 5,000 indicated horsepower (3,700 kW) and could make 20.5 knots (38.0 km/h; 23.6 mph).

They were arranged as a pair of revolving deck mounts, a pair of fixed deck mounts (deleted in the later vessels) and a single bow-mounted tube; three reloads were provided.