Why a British carrier lead might not trigger an immediate race

Without treaty conversions, American and Japanese responses to a large British carrier force would begin from purpose-built ships and could be slowed by politics and different strategic interpretations.

Question

How would the United States and Japan respond to a large Royal Navy carrier force in a world without treaty conversions?

Short answer

They would likely respond slowly, because both needed purpose-built programs and Britain could justify its carriers as worldwide trade protection.

Notes

In a non-treaty world, Lexington and the Japanese capital-ship conversions remain in their original roles, leaving Langley and Hosho as the early carrier starting points. The United States would have to persuade Congress to finance purpose-built carriers, while Japan could choose to build successors to Hosho. Britain could portray its carriers as instruments for trade protection across worldwide commitments. Observation and delayed competition are more likely than an immediate race, with a stronger response in the 1930s.