He was also instrumental in some reforms to the training and equipment of British soldiers after the defeat in France in 1940, intended to meet the demands of modern warfare.
[23] He later attended the Staff College, Camberley as a student from 1924 to 1925, his fellow students including Reade Godwin-Austen, Ivor Thomas, Douglas Graham, Noel Beresford-Peirse, Humfrey Gale, Archibald Nye and Willoughby Norrie, Daril Watson, Vyvyan Pope, Thomas Riddell-Webster and Otto Lund.
[4] At the start of the Second World War in September 1939, Irwin, promoted to temporary brigadier on 15 March 1939,[24] headed the 6th Infantry Brigade,[4] part of the 2nd Division.
[27] On 7 November 1941 Irwin, promoted to the acting rank of lieutenant-general,[28] commanded the XI Corps, which was based in East Anglia and had substantial responsibilities for the defence of Britain in the event of a German invasion.
On 6 April 1943, Irwin gave a press conference in which he criticised the equipment, training and motivation of the Allied armies in India.
After three years as Commander-in-Chief of British forces of the West Africa Command,[4] during which time he was promoted to the permanent rank of lieutenant general, he retired to private life in 1948.
He was Mentioned in Despatches four times but significantly, he never received a knighthood, which would normally be expected for an officer of substantive lieutenant general rank.