M.1/30 was one stage in the requirements that led to the Swordfish. It was combined with S.9/30 to become S.15/33. The earlier specification therefore needs to be read with that later combination in mind.
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How M.1/30 became S.15/33
Combining M.1/30 with S.9/30 produced S.15/33, the later requirement on the route to the Swordfish.