An Astute-class submarine in the Second World War

What would happen if Britain received Astute-class production and support infrastructure in 1930, but had to use period weapons?

Britain would gain submarines able to remain submerged, outpace period fleets, and shift rapidly between distant theaters, even while using contemporary torpedoes.

The scenario transfers the infrastructure, supply chains, and personnel needed to build and support Astute-class submarines to Britain in 1930, while retaining period weapons. Their ability to remain submerged and outpace contemporary fleets would transform interception. Italian ships could face attacks whenever they put to sea, while submarines could watch German departures. In the Pacific example, a nuclear submarine could race ahead of Japanese carriers returning from Pearl Harbor and wait near Japan. The proposed advantage comes chiefly from sustained underwater speed and strategic mobility, even without modern torpedoes.