The arms of the county of Lincoln with an eagle above (unofficial)
No. 503 (City of Lincoln) Squadron RAF was an auxiliary squadron of the Royal Air Force. It operated as a bomber squadron in the 1920s and 1930s, but was disbanded before the outbreak of the Second World War.
The squadron was formed on 5 October 1926 at RAF Waddington in Lincolnshire as No. 503 (Bombing) Squadron of the Special Reserve, manned by part-time volunteers. It was at first equipped with Fairey Fawn light day bombers. It re-equipped with the partly wooden Handley Page Hyderabad heavy night bomber in 1929, receiving the improved, all-metal Handley Page Hinaidi from 1933. Some squadron members thought the Hyderabad superior to the Hinaidi, but when a squadron member discovered 'Fungae Lachrymosis' in the longeron of a Hyderabad they settled for the newcomer, some almost having spent their life of 700 flying hours already.
In October 1935, it changed role again to become a day bomber squadron, receiving Westland Wallaces. These were replaced by the Hawker Hart in June 1936, these in turn starting to be replaced by the updated Hawker Hind in July 1938. However, in 1938 it was decided to switch the role of the Auxiliary Air Force to that of air defence, and on 1 November 503 Squadron was disbanded by renumbering it to No.616 (South Yorkshire) Squadron and moving it to RAF Doncaster.
Jackson, Robert The Encyclopedia of Military Aircraft. Parragon Books Ltd., 2006. ISBN 1-4054-2465-6.
Jefford, Wing Commander C.G., MBE, BA, RAF (Retd). RAF Squadrons, a Comprehensive Record of the Movement and Equipment of all RAF Squadrons and their Antecedents since 1912. Shrewsbury, Shropshire, UK: Airlife Publishing, 2001. ISBN 1-84037-141-2.