A military airfield, used in both World Wars to the present day. It was one of the earliest military aerodromes to be built, opening in 1915, with some flight sheds and a twin hangar, nothing remains of this phase. Between 1925-30 an 'A' type hangar, barrack blocks and messes were built. By 1939 a 'C' type hipped hangar and five 'H' type barrack blocks were added. It was heavily committed during the Battle of Britain in 1940, when it was a Sector Airfield of the hard-pressed 11Group. During WW2 the buildings were all carefully camouflaged and painted to represent houses with gardens and as a result suffered little bomb damage. As the war progressed and more use was made of Northolt new construction continued and fourteen blister hangars were built around the aerodrome in 1943. The runways were also improved between 1943-1944. Polish squadrons occupied the site in 1940-4 and a Polish war memorial is located on the outskirts of the site, in addition to the Spitfire memorial inside the airfield. After the war the airfield became an airport for London but reverted to the Royal Air Force when Heathrow opened in 1954. Post-War development included new airfield buildings such as a new control tower and sergeants mess facilities.