Draft memorandum by Vice-Admiral Sir Henry Oliver [Chief of Admiralty War Staff] on the importance of keeping Britain's possession of the German naval codes secret, suggesting that a daily summary of information from German intercepts be given to the Commander-in-Chief, Grand Fleet [Admiral Sir John Jellicoe] in person, rather than risk using the telegraph. Also includes: a covering note from Oliver to the First Lord of the Admiralty, Arthur Balfour, suggesting that a letter from him on the subject would carry more weight; a rough draft of the resulting letter by Oliver, annotated by Balfour; and the finished copy of Balfour's letter to Jellicoe.