German battlecruiser intelligence shaped the Admiral class

Apart from Room 40, did prewar naval intelligence materially affect fleet decisions?

Yes; intelligence shaped war estimates and led the Admiral class to answer a later German battlecruiser design than the ship then under construction.

Naval intelligence estimates affected decisions about war and the opponents a fleet expected to face. British planners obtained details of a German battlecruiser design when selecting the Admiral class. They believed those details described the ship entering construction, but the account identifies them as plans for its intended successor. The British design consequently answered a more advanced anticipated opponent. American intelligence also existed before the war, although difficulty securing government funding is identified as a constraint on its work.