Germany's construction could provide a legal or diplomatic grievance, but enforcing the Versailles restrictions ultimately required effective multinational sanctions or war. Neither course had dependable political support in 1935. The League of Nations lacked a mechanism that could make sanctions effective without broad cooperation, while the British public was unlikely to support war over two new German battleships. Negotiating a ratio therefore converted an unenforceable prohibition into an acknowledged British numerical advantage. The agreement is presented as a response to enforcement limits, rather than evidence that Britain welcomed German rearmament.
Notable Point · 46:22-48:17
Why Britain negotiated German naval limits
The Anglo-German Naval Agreement reflected Britain's weak practical options for enforcing Versailles without public support for sanctions or war.