Editing GCHQ (section)

===World War I===
During the First World War, the [[British Army]] and [[Royal Navy]] had separate signals intelligence agencies, [[MI1b]] and [[NID25]] (initially known as Room 40) respectively.<ref>{{cite book |first=Paul |last=Gannon |title=Inside Room 40: The Codebreakers of World War I |publisher=Ian Allan Publishing |year=2011 |isbn=978-0-7110-3408-2}}</ref><ref>Johnson, 1997, p. 27</ref>