Fifty-three T Class submarines were eventually constructed, making it the largest class of ocean-going submarines ever built for the Royal Navy. The original order for the class was made under the growing threat of war, which forced the Admiralty to open its purse-strings, and no fewer than 21 riveted-hull T boats, built between 1937 and 1941, followed Triton.
Displacing almost 400 tons less than the O, P and R Classes, this first group of 22 T Class submarines was noted for its simplicity of construction. They were superior to the O, P and Rs in that they had greater submerged speed, better surface and underwater handling and more torpedo tubes. However, because the displacement limitations restricted the size and power of their engines to 2500 hp surfaced (1450 hp submerged), maximum surface speed was reduced.
