Tim Dealtry's parents were Percy Dealtry, joint founding headmaster of The Leas, and his wife Margaretta Lawrence, daughter of Edward Lawrence, an East India merchant.
Tim served in World War 1, volunteering shortly after he had left Charterhouse; on 27 April 1915 he was appointed 2nd Lieutenant, Signal Company, West Lancashire Divisional Engineers. On 1 Jul 1917 he was appointed Lieutenant, Royal Engineers (seniority from 1 Jun 1916); and on 12 Apr 1919 he was invalided out as Lieutenant, Royal Engineers, Territorial Force. It is generally assumed that some war injury was responsible for his unusual gait: he is described as always walking with one hand grasping his bottom.
After his war service, Tim studied at University College, Oxford; in the class-lists of 16 July 1920, he "satisfied the examiners" in the shortened course (for war veterans) of Modern History. His MA was conferred on 28 March 1925.
After satisfying the Oxford examiners, Tim taught at a couple of prep schools: first at Stanmore Park, under Vernon Royle; then under Orlando Wagner at his school in Queen's Gate, London. When Tim's father retired in 1925, Tim joined CJH Barr as joint headmaster of The Leas. It was at this time that The Leas School (Hoylake) Ltd was set up to manage the school.
Tim organised the school's wartime evacuation to Glenridding in 1940, intending to let the Hoylake buildings to John Holt & Co (Liverpool) Ltd, an international trading company (later John Holt plc) then based in the Liver building, Liverpool. The letting plan had to be abandoned when the RAF requisitioned the buildings in 1941. The nature of the RAF's use of the building was secret during the war; in 1945 it was made public that the buildings had been used as a rehabilitation hospital for non-commissioned men with serious physical injuries.
Ironically, in May 1941 four High Explosive bombs were dropped near Lantys Tarn (killing two sheep), falling closer to Glenridding than any bombs, even incendiaries, to The Leas throughout the war.
Tim was obliged to retire from headmastership of The Leas in 1944, while the school was still in Glenridding. From 1947 until just before his death he worked for the Incorporated Association of Preparatory Schools.
In 1923 Tim had married (Lucy) Isabel Hood Daniel, widow of Arnold Frost Hood Daniel, college lecturer; she was a daughter of John Andrew Edward Rayner, chemicals manufacturer, and his wife Emily Agnes Kemble, of the same theatrical family as Mrs Siddons (Sarah Kemble), Charles Kemble, etc. Tim and Isabel had two sons, both born at The Leas.