This chapter explores how British military intelligence organizations managed large amounts of information during World War I and World War II. It discusses how the MI5 registry and the London Reception Center developed indexing systems to organize intelligence on individuals and topics. It also examines how Bletchley Park's Government Code and Cypher School indexed intercepted communications to support codebreaking efforts. The chapter argues these organizations performed information management roles like modern information officers by obtaining, organizing, and sharing intelligence with decision makers.