The Public Record Office has records from the British Cabinet Office, Colonial Office, War Office, Foreign Office and the Dominions Office that are relevant to William Morris Hughes research.

Cabinet Office

CAB21/111: Committee on Australian Purchases, 1918.

CAB23: War Cabinet (1916–19) and Cabinet (1919–22) minutes.

CAB24: War Cabinet (1916–19) and Cabinet (1919–22) memoranda &c.

CAB27/43: Committee on Indemnity, 1919.

CAB29/28: Peace Conference: British Empire Delegation. Minutes.

CAB37: Photographic copies of Cabinet Papers, 1870.

CAB42: Photographic copies of the papers of the War Council, Dardanelles Committee and War Committee, 1915–16.

Colonial Office

CO418/132-186: Australia: Governor-General, despatches, 1915.

CO532/78: Canada: Governor-General, despatches, 1915.

CO537: Supplementary original correspondence.

CO616/9-30: German control of metal productions.

CO881/15: Correspondence with the base metal industry.

War Office

WO163/21-22: Army Council, minutes, 1916.

Foreign Office

FO371: General correspondence: official [Far East Affairs, Japan].

FO800:
Arthur James Balfour, papers.
Earl Curzon, papers.
Sir Edward Grey, Viscount Grey of Fallodon, papers.

Dominions Office

See the Australian Joint Copying Project Handbook Part 10 (National Library of Australia, 1991) for extensive references – not indexed.

See the National Archives, United Kingdom website.