Papers relating to his command of 1 Infantry Div, Anzio, Italy, 1944, dated 1943-1962, principally comprising correspondence and memoranda, 1943-1944; diary and typescript diary entries, 1943-1944; operation orders, tactical notes and maps, 1944; written accounts of operations carried out by 1 Div and individual regiments and battalions, 1944; correspondence relating to historical accounts of the landings, 1945-1962, notably Anzio by Wynford Vaughan Thomas (Longmans, London, 1961). Other papers relating to his life and career, 1920-1958, notably including an article by Penney on his service in Wazaristan, India, 1937, reprinted from the Royal Signals Quarterly Journal, Oct 1938 and Jan 1939; memoranda from General Staff, Shanghai, from the City Government of Shanghai and from W R Connor Green, British Embassy, Tokyo, concerning relations between the Chinese and Japanese, and the role of the British garrison in the protection of Shanghai, 1931-1933; diary, 1932, referring principally to matters affecting British troops in Shanghai; press cuttings, [1932]; anti-Japanese propaganda posters produced by the Shanghai Municipality National Salvation Committee to Resist Japan, [1932]; itinerary of Penney's movements in the Middle East and North Africa, 1941-1943; diary, 1943-1944, including description of Allied Forces HQ, Algiers, and reflections on the differences between US and British signals procedure; official and personal correspondence relating to his service as Director of Intelligence, HQ Supreme Allied Commander, South East Asia, [1945].

Unpublished typescript memoirs, 1893-1969, including: accounts of life in the British colony in St Petersburg before World War One; work in the British Military Mission at the Russian War Office; events witnessed during the Russian Revolution and conditions for the Russian Army during the Revolution, 1917-1918; evacuation of British personnel from Russia, February 1918; negotiating with Finnish Red and White commanders while travelling through Finland during the Civil War; liaising with Admiral Aleksandr Vasiliyevich Kolchak and the White armies in Harbin, China, 1918; liaising with General Mikhail Konstantinovich Dieterichs, Czechoslovak Legions, and a special mission to Ataman Grigory Mikhaylovich Semyonov (or Semenov) in Chita, Transbaikalia, November 1918; activities as General Sir Harry Knox's liaison officer at the White Army Headquarters in Omsk, November 1918 - November 1919; the retreat from Omsk to Vladivostock following the success of the Bolshevik army, November 1919 - March 1920; stationing in Gibraltar and Egypt, 1921-1922; life and work in Simla, Waziristan and Kamptee, India, 1922-1928; work as an intelligence officer, Meshed, Persia (Iran), 1928-1931; life and work in Bombay, Ajmer, Jhansi, Alwar and Delhi, India, 1932-1935, including description of rioting under the Maharajah of Alwar; experiences working in India, China and Egypt during World War Two, including visit to Palestine; account of working in the post-war timber trade and as a consultant in the Russian Section of the London Chamber of Commerce. Also article 'Anglo-Russian Timber Trade: Personal Reminiscences and Reflections of Col L Steveni', The Timber Trades Journal , 11 March 1961, and article by Richard J Aldrich, University of Nottingham, from Modern Asian Studies 32, 1 (1998), pp. 179-217, entitled "Britain's Secret Intelligence Service in Asia during the Second World War" including analysis of Steveni's role as Director of British Secret Intelligence Service (SIS) in Asia.

Papers relating to his service in the Indian Army, dated [1941], 1942, [1944], 1947, 1962-1964, 1970, 1973, 1984, principally comprising photographs of convoys at Sarwekai on the route between Mangai and Wana, South Wazaristan, India, [1941]; operation instructions for 50 Parachute Bde exercise in Tughlakabad area, India, Mar 1942; 'Some notes on Gurkhas', typescript text by Stevenson-Hamilton, 1943; typescript account of the service of 4 Prince of Wales's Own Gurkha Rifles, India, 1943-1944, written by Stevenson-Hamilton in [1944]; typescript account of the service of 2 Bn, 4 Prince of Wales' Own Gurkha Rifles, Italy, 1944, written by [Stevenson-Hamilton] in [1944]; unsigned official notes on a tour of Arakan by 98 Indian Infantry Bde, Burma, 1944; 71 Indian Infantry Bde instructions for operations in Maungdaw, Burma, Apr 1944; typescript text on Gurkha operations in Wazaristan and the Punjab, India, 1947, and on the proposed transfer of Gurkha regiments to the British Army, 1947; notebook containing notes on misdemeanours and crimes committed by soldiers at Garlochhead Training Camp, Helensburgh, 1962-1964.