After the 1935 programme, the Royal Navy stopped ordering S-class boats and shifted development toward the larger T class. Britain's abandonment of the Ten Year Rule in 1932 set planners looking toward a major risk period beginning around 1942. The service expected to expand production during the three years before that danger window, making a proven S-class design useful even after peacetime procurement had moved on. Design maturity and available industrial capacity could therefore return an established submarine type to large-scale wartime production.
Notable Point · 14:47-16:16
The Ten Year Rule and the Royal Navy's 1942 submarine plans
The end of new S-class orders, the shift toward the T class, and Britain's abandonment of the Ten Year Rule frame plans to expand submarine production before a 1942 risk period.