The intelligence value of the Anglo-German Naval Agreement

What did Britain gain from the 1935 Anglo-German Naval Agreement?

It gained access to German naval activity and shipyards, turning the agreement into an intelligence-gathering opportunity as well as an arms-control measure.

Doubts that Germany would keep the agreement did not remove its intelligence value. The agreement connected German building to treaty categories and created legitimate access to German yards. Open visits showed both what the Germans were prepared to reveal and what they tried to conceal, guiding later intelligence collection. Britain used the opportunity to visit German yards, while Germany did not take up the corresponding chance to visit British yards.