1:600 "L" 'type 2' class submarine - HM Submarine L26 in this case © Andrew Arthur

Originally, these boats were designed as improved "E" class submarines - WW1 workhorses - but with a "saddle-tank" configuration. The scale of the improvements prompted the admirality to dexignate them a class in their own right.
They were roughly divided into three sub-groups;

1. 4 x 18" bow tubes, 2 x 18" beam tubes
2. 4 x 21" bow tubes, 2 x 18" beam tubes ( latter omitted later )
3. 6 x 18" bow tubes, 2 x 4" AA guns

Forward of the conning tower a gun was shipped, originally a 3" AA and then a 4" AA type.
The "L" class formed the backbone of the British submarine flotillas during the 1920's. They served from the Home waters to the China Station. The first "L" boats were despatched to China in 1919, twelve boats of the class served in the China Station.
By 1929 there were only 30 boats remaining in service, ten of these held in reserve in Home waters. By 1939 only three were left in existence, these saw some operational employment during 1940 otherwise they were used for training purposes.
In 1944 the boats were sent to Canada where they finished their days giving anti-submarine training to convoy escort groups.