It was the fall of France that caused the problems for the RN, firstly due to the lack of escorts caused by the invasion scare, ( first happy time) secondly by the improved logistics that bases in France gave to the U boats.Granted they had to learn lessons about the best place to hunt UBoats, but the “failed” tactics the RN used in 1939 Hunter killer groups guided by enigma intercept was the same succsesful tactics used by Hunter killer groups in 1944.
I don't disagree; the hunting groups of 1944 were following the same tactics as they were in 1939. However, they could only be useful once the convoys were sufficiently well escorted to protect them against any subs that leaked past the hunting groups. In 1939 and 1940, the RN didn't really have enough long-range escorts to sufficiently protect convoys from end-to-end, problems which were exacerbated by the invasion scares, by the need to supply ships to the hunting groups (albeit only in 1939), and by the practice of removing ships from convoy escorts to hunt close contacts (within a few hours steaming). The German move to French bases allowed them to reach the exposed convoys in the Mid-Atlantic; these convoys might have been sufficiently escorted for the WWI environment, but were exposed against a wolf-pack. Had the RN been expecting this change in tactics, they would have prioritised construction of ASW vessels prior to 1938.
I'm not sure that actually studying WWI was done that well or deeply and combined with self deception about the likelihood of U boats following prise rules...
Chapter 1 on WWI http://www.ibiblio.org/hyperwar/NHC/NewPDFs/UK/UK, Defeat-of-Enemy-Attack-on-Shipping1939-1945.pdf
This is certainly an older stereotype, but newer scholarship, such as George Franklin's Britain's Anti-Submarine Capability 1919-1939 or D K Brown's Atlantic Escorts : Ships, Weapons and Tactics in World War II, paints a different picture. The need for convoy was well understood - the Shipping Defence Advisory Committee, formed in 1937, drew up an effective convoy plan. The main failings were the misunderstandings about the capability of convoy escorts relative to hunting groups (understandable, given the WWI situation), and a lack of contingency planning for the Fall of France, a problem that was more political in nature. There was likely no real self-deception about U-boats following prize rules - quoting Brown, in respect to an agreement about submarines following prize rules: 'there was little confidence that this would be maintained'.