Croydon Airport (ICAO: EGCR) was the United Kingdom's main international airport during the interwar period. It opened in 1920, located near Croydon, then part of Surrey, using a temporary terminal, hangars and offices on Plough Lane. A new permanent terminal in a Neoclassical style opened in 1928 on the 1925-built Purley Way The airport handled more cargo, mail, and passengers than any other UK airport at the time. Innovations at the site included the world's first air traffic control, the first airport terminal and the world's first airport hotel (the Gate Lodge, now the Aerodrome Hotel). It was home to Britain's first national airline, Imperial Airways, founded through a government sponsored four-airline merger in 1924. During the Second World War the airport was named RAF Croydon as its role changed to that of a fighter airfield during the Battle of Britain; and in 1943 RAF Transport Command was founded at the site, which used the airport to transport thousands of troops into and out of Europe.

After the war, its role returned to civil aviation, but the lack of available land for expansion meant that the role of London's primary international airport later passed to London Heathrow Airport. Croydon Airport closed in 1959. It had been known under eight different names while it was active.

In 1978, the terminal building and Gate Lodge were granted protection as Grade II listed buildings. In May 2017, Historic England raised the status of the terminal building to Grade II*. Owing to disrepair, the Gate Lodge is now classified as Heritage at Risk by Historic England.

In December 1915, Beddington Aerodrome was established – one of a number of small airfields around London that were created for protection against Zeppelin airship raids during the First World War. In January 1916, the first two aircraft, B.E.2Cs, arrived at the aerodrome as part of Home Defence. Waddon Aerodrome opened in 1918 as part of the adjoining National Aircraft Factory No. 1, to serve aircraft test flights. The two airfields were on each side of Plough Lane, Beddington to the west and Waddon to the east.

Beddington Aerodrome became a large Reserve Aircraft and Training aerodrome for the Royal Flying Corps. After the end of the First World War the aerodrome became an important training airfield for the newly formed Royal Air Force. During 1919, Prince Albert (later George VI) gained his "wings" here with No. 29 Training Squadron, the first member of the royal family to learn to fly. His elder brother, the Prince of Wales (later Edward VIII), also received flying training with No. 29 Training Squadron at Beddington during 1919.

The following units were also here at some point:

Beddington and Waddon aerodromes were combined to become Croydon Aerodrome, the gateway for all international flights to and from London. The new, single aerodrome opened on 29 March 1920, replacing the temporary civil aerodrome at a Cavalry ground on Hounslow Heath. Plough Lane remained a public road crossing the site. Road traffic was halted when necessary, first by a man with a red flag and later by a gate. The aerodrome stimulated a growth in regular scheduled flights carrying passengers, mail and freight, the first destinations being Paris, Amsterdam and Rotterdam. Two flights daily from Paris were scheduled for ease of communication with London during the Paris Peace Conference. In 1923, flights to Berlin Tempelhof Airport began.

Penshurst Airfield was an alternative destination for airliners when Croydon was closed on account of fog. One such diversion was on 24 September 1921, when a de Havilland DH.18 aircraft was diverted to Penshurst. This situation lasted until Penshurst closed on 28 July 1936.