Deedes was born on 10 March 1883, the son of Colonel Herbert and Rose Deedes. He was educated at Eton.
After leaving school, Deedes joined the army, where his first post was in the King’s Royal Rifle Corps in South Africa. In 1910- 1911, he was involved in reforming the Ottoman gendarmerie of northern Libya. In 1913, he was posted to Anatolia and seconded to the Turkish Interior Ministry by the Foreign Office.
World War One
On the outbreak of World War One, Deedes joined the War Office intelligence department. He was drafted as Staff Captain for Gallipoli campaign, and later posted to Cairo, working with those planning the Arab Revolt.
By the end of the War he had been posted as Administrator in Jerusalem. It was during this period that he became familiar with Zionism, of which he became a lifelong supporter.
Deedes resigned from the army in1923 and returned to England, where he became heavily involved in social work and devout Anglicanism, while still travelling and promoting Zionism. Labour member on the London county council for Northeast Bethnal Green 1941-1946.
Died 2 Sept 1956, at St. Bartholomew’s Hospital, London.