In January 1920, Cochrane was removed from the Navy List and granted a commission in the
Royal Air Force. He served in various staff positions and commanded
No. 3 Squadron from 1924 before attending the RAF Staff College and commanding
No. 8 Squadron from 1929. He attended the
Imperial Defence College in 1935. At the request of Group Captain
T. M. Wilkes, New Zealand Director of Air Services, the Air Ministry sent Cochrane to New Zealand in 1936 as an advisor for the establishment of a military aviation service that would be independent of the army. His report and recommendations was produced at the end of the year and this would lead to the creation of the
Royal New Zealand Air Force (RNZAF). He was subsequently invited to lead the raising of the RNZAF and on 1 April 1937, he was appointed
Chief of the Air Staff (CAS), the rank of group captain. For the next two years, he worked on the expansion of the RNZAF in line with his recommendations, including the establishment of a flying training school at Wigram Air Base. In March 1939, his term as CAS ended. , King
George VI and Group Captain
John Whitworth discussing the Dambusters Raid in May 1943 ==Second World War and the post-war years==