Why the Royal Navy expected submarines everywhere

The 1914 loss of the armoured cruisers Aboukir, Cressy, and Hogue became an enduring institutional warning about predictable movement in a submarine threat area. By the Second World War, Royal Navy cruisers were expected to avoid stopping, straight courses, and regular timing even when no submarine had been sighted. This habit could also frustrate a long-range surface torpedo attack because constant course and speed changes make a firing solution harder to predict. The advantage would come from First World War experience and anti-submarine caution rather than from a uniquely complete British understanding of Japanese torpedo performance.