The Royal Navy could foresee useful escort-carrier roles, especially against Germany, but could not treat them as substitutes for fleet carriers. Designs for merchant conversions existed by 1936, yet scarce money and industrial capacity went to higher-priority fleet carriers, destroyers, aircraft, and wider rearmament. Planners also expected France and Norway to remain available, which made land-based air cover appear more dependable than it proved in 1940. The concept was understood before the war, even though the Treasury and competing rearmament demands kept it from becoming a funded program.
Chapter · 2:00-14:21
Why Britain did not build escort carriers before the war
Treaty tonnage, Treasury limits, and competing rearmament demands explain why prewar escort-carrier plans did not become ships.