British Royal Navy planning building G-class submarines according to the Dutch magazine Marineblad dated 1916-1917 no. 7

An item referred to the magazine Engineering Weekly dated 11 August 1916 reporting that the British Admiralty intended to built a new class of powerful submarines called the G-class. Recently was the F-class submarines built with a submerged displacement of 1.200 ton. This class was fitted out with 5.000 hp diesels for surfaced and 2.000 hp electro engines for submerged propulsion. The G-class submarines were to have a length of around 225’ with a submerged displacement of 1.500 ton. Diesel engines supplying 6.500 hp and electro engines supplying 2.400 hp were available fore respectively surfaced (allowing a speed of 24 miles) and submerged propulsion.