Most K-class boats left service by 1926, and the 1930 London Naval Treaty finally ended K26's career. The story did not stop with the completed steam submarines, however. Orders for K18, K19, and K20 were cancelled and their positions on the stocks were used for new M-class submarines. In this reading, that connection unhappily continued the same appetite for unusually large and complicated undersea designs. This short procurement afterlife places the K class within a broader history of Royal Navy submarine experimentation rather than treating it as an isolated failure.
Notable Point · 42:17-43:31
Cancelled K-class orders carried into the M-class programme
K18, K19, and K20 were cancelled before completion, but their places in the building programme became M-class submarines, extending the legacy of experimental large-submarine procurement.