Dening was a career foreign service officer; and he was promoted regularly across the span of years.
During the First World War Dening served with the Australian Imperial Force (service record). While serving with 31 Battalion AIF he was wounded in the Attack at Fromelles on 19 July 1916 and evacuated to England with shell shock. He later rejoined the 2nd Division as intelligence officer and was awarded an MBE in 1919.
Dening was consular officer in 1938, when he was awarded an OBE.  During the Second World War, he served on the staff of Louis Mountbatten, 1st Earl Mountbatten of Burma. He had become the Chief Political Adviser to the Supreme Allied Commander, South-East Asia Command when he was made a member or Companion in the Order of St Michael and St George in 1945.
In 1950, Dening was an Assistant Under-Secretary of State in the Foreign Office when the King promoted him to be a Knight Commander of the Order of St Michael and St George. He was the British Political Representative in Tokyo in 1950-1951 and when full diplomatic relations were re-established, his role was an essential element of the transition.
In 1955, Sir Esler promoted to be a Member of the First Class, or Knight Grand Cross, of the Order of St Michael and St George.
- Order of the British Empire, Member Military Division (MBE), 1919.London Gazette 3 June 1919 page 6812
- Order of the British Empire, Officer (OBE), 1938.
- Order of St Michael and St George, Companion (CMG), 1945.
- Order of St Michael and St George, Knight Commander (KCMG), 1950.
- Order of St Michael and St George, Knight Grand Cross (GCMG), 1955.
- Japan (1960)
- The Life of Toyotomi Hideyoshi (1971)
- Ian Nish. (2004). British Envoys in Japan 1859-1972, pp. 173-178.
- "No. 34585". The London Gazette. 30 December 1938. p. 14.
- "No. 37119". The London Gazette. 8 June 1945. p. 2938.
- "No. 39092". The London Gazette. 15 December 1950. p. 6269.
- Hoare, James. (1999). Embassies in the East: the Story of the British Embassies in Japan, China, and Korea from 1859 to the Present, p. 214., p. 214, at Google Books
- The first British Ambassador to Japan was appointed in 1905. Before 1905, the senior British diplomat had different titles: (a) Consul-General and Envoy Extraordinary and Minister Plenipotentiary, which is a rank just below Ambassador.
- "No. 39569". The London Gazette. 10 June 1952. p. 3185.
- "No. 40497". The London Gazette. 3 June 1955. p. 3261.
- "No. 47147". The London Gazette. 11 February 1977. p. 2079.
- WorldCat Identities Archived 30 December 2010 at the Wayback Machine.: Cortazzi, Hugh
- Hoare, James. (1999). Embassies in the East: the Story of the British Embassies in Japan, China, and Korea from 1859 to the Present. Richmond, Surrey: Curzon Press. ISBN 9780700705122; OCLC 42645589
- Nish, Ian. (2004). British Envoys in Japan 1859-1972. Folkestone, Kent: Global Oriental. ISBN 9781901903515; OCLC 249167170
- UK in Japan, Chronology of Heads of Mission