Correspondents on defence inventions and suggestions from the general public include: Richard Powell [Assistant Private Secretary to the First Lord of the Admiralty] (3); Desmond Morton [Director, Industrial Intelligence Centre]; Sir Christopher Bullock [Permanent Secretary], Air Ministry; Ralph Assheton [later 1st Lord Clitheroe]; Colonel George Turner [former Superintendent, Design Department, Royal Arsenal]; Lieutenant-Colonel Charles Thoroton on the advantages of Admiralty control of the Fleet Air Arm and various naval bases; John Chalk, Imperial College of Science and Technology, on his designs for ship-borne submarines (6); P Warburton [Assistant Secretary], Committee of Imperial Defence (5); Katharine, Duchess of Atholl; Lieutenant-Colonel Sir Hugh Elles [Master General of Ordnance]; Hugh Frewen on ordnance experiments (3); [Alfred] Duff Cooper [later 1st Lord Norwich], Secretary of State for War (2); Harry Sellar [Private Secretary to the Minister for Co-ordination of Defence].Other subjects include: using short wave radio for communication and air defence purposes; fighter cover for London, the difficulties caused by increased bomber speed, and the use of balloon curtains; German intentions towards Austria, and anxiety to keep on good terms with Britain; low RAF morale; surplus arms.Also includes: copy of a letter from Sir Christopher Bullock to Sir Herbert Creedy [Permanent Under-Secretary of State for War] on a proposed carbide factory for use in munitions and aircraft production, with notes on the use of carbide in aircraft welding and the general uses of acetylene and carbide; copies of letters from Colonel George Turner to [William] Collin Brooks [Editor, Sunday Dispatch] and to the Daily Mail on their pro-German position; copy of an article by Turner for the Daily Mail on the early development of bombing, the ineffectiveness of anti-aircraft defences, the air threat from Germany and the need for a Ministry of Defence; print of John Chalk's submarine carrier design; copies of correspondence by Violet Pearman [Secretary to WSC] to individuals listed above, and also to others including F A Lindemann [later 1st Lord Cherwell] and Admiral Bertram Chambers.