In 1919 he attended the first post-war course at the Staff College, Camberley, and was then appointed a Deputy Assistant Adjutant-General in the War Office before spending four years as an instructor at the School of Military Administration from 1921 to 1925. While there he wrote the first edition of the textbook Military Organisation and Administration that lasted through 29 editions into the 1960s. After this he was appointed instructor in military administration at the Staff College 1925–1928. Attendance at the Imperial Defence College in 1930 was followed by a post as General Staff OfficerGrade 1 at the War Office, 1930–1933. In 1931 he became a full colonel and in 1933 he became a brigadier and commandant of the Senior Officers School in Sheerness, then deputy military secretary in the War Office 1935–1936, before becoming commander of Royal Artillery 4th Division, 1937-1938.
World War II
He was promoted to major-general in command of Administration for Southern Command, 1938–1939 and was appointed the quartermaster-general on mobilisation of the British Expeditionary Force in France and Belgium, 1939–1940, until the evacuation from Dunkirk. After Dunkirk he became quartermaster-general of Home Forces and set about re-building the army from Kneller Hall in Twickenham. After a year he became senior military advisor to the Ministry of Supply under Sir Andrew Duncan and Lord Beaverbrook. In less than a year the army had thirteen fully equipped and trained divisions to repel a German invasion. In 1942 he became one of General Montgomery's team to revitalise the Eighth Army as lieutenant-general in charge of administration in GHQ Middle East. In a broadcast concerning the capture of Tripoli the British Secretary for War, Sir P.J. Grigg, said that much of the credit for the Eighth Army's phenomenal advance was due to the quartermaster-general's staff under Lt General Sir Wilfrid Lindsell. During the Second World War he was mentioned in dispatches on three more occasions. At the end of 1943 he moved east to become principal administrative officer in GHQ India prepared General Slim's Fourteenth Army to attack the Japanese in Burma. Here he played the most significant role in mobilising Indian resources, establishing production capabilities and building the foundations for the Indian defence industry. After returning from India he was attached to the Board of Trade to co-ordinate the clearing of factories for peacetime production.