Air Transport Auxiliary (ATA) came into existence soon after the outbreak of war in September 1939. Its flag was finally hauled down on 30th November 1945. In these six years it grew from an idea in the mind of Gerard d'Erlanger to an organisation employing at its peak in 1944, 550 male pilots, 108 women pilots, 109 flight engineers and a ground staff of about 2800, a total of around 3500 people.

Experience leads me to the conclusion that the coefficient of relative man-power (and hence economic) efficiency of a specialised civilian as opposed to a necessarily unspecialised Service organisation is between 3 and 5, hence that ATA released for more direct operational war services between 9000 and 15000 men and women.