Would an early Type XXI prompt British intervention?

Could Britain respond to a German Type XXI in the 1930s by intervening before Germany built more?

Clarke considers Paul from Chicago's suggestion possible but unlikely under the British governments of the period.

Paul from Chicago suggests that an early German Type XXI might lead Britain to intervene before more boats were built. Clarke regards that response as unlikely under the British governments of the 1930s. He leaves it as a possibility rather than an expected consequence.