White Waltham Airfield (ICAO: EGLM) is an operational general aviation aerodrome located at White Waltham, 2 nautical miles (3.7 km; 2.3 mi) southwest of Maidenhead, in the Royal Borough of Windsor and Maidenhead in Berkshire, England.

This large grass airfield is best known for its association with the Air Transport Auxiliary from 1940 to 1945 and also has a significant history of prewar flying training, wartime and postwar RAF use and postwar use as a flight test centre by the Fairey and Westland aircraft companies. In the mid-1950s it was HQ of RAF Home Command. It is now privately owned and is the home of the West London Aero Club.

The airfield was set up in 1928 when the de Havilland family bought 196 acres (0.79 km) of grassland to house the de Havilland Flying School. In 1938 the airfield was taken over by the government, and during the Second World War was the home of the Air Transport Auxiliary between its formation in early 1940 and disbandment during September 1945. The ATA staged a unique Air Display and Air Pageant at White Waltham on 29 September 1945 which was opened by Lord Beaverbrook and featured a memorable static park of Allied and German aircraft and the flying included Alex Henshaw displaying a Seafire Mk45.

After the war, the airfield was also used by Fairey Aviation and later Westland Helicopters, which assembled and tested aircraft built at their Hayes factory. These included the Fairey FB-1 Gyrodyne (1947), Fairey Jet Gyrodyne (1954), Fairey Ultralight (1955), Fairey Rotodyne (1957) & Westland Scout (1960) & Westland Wasp (1962). The prototype Fairey Gannet was first flown from Aldermaston but production aircraft were completed and first flown at White Waltham too. The example that was stored at the airfield has now been moved to the Solway Aviation Museum at Carlisle Lake District Airport where restoration is ongoing.

Prince Philip, Duke of Edinburgh, was taught to fly at White Waltham in 1952, flying a de Havilland Canada DHC-1 Chipmunk belonging to HQ RAF Home Command Communications Squadron (HCCS) of the Royal Air Force. This squadron was based at the airfield from 1950 until 1959.

On 28 January 1961 the HQ of No. 25 (Flying Training) Group RAF, responsible for administering the Flying Refresher Schools and the Advanced Flying Schools moved from RAF Manby to RAF White Waltham. The group was operational for a further seven years, before eventually disbanding on 1 June 1968, and was absorbed into No. 22 Group RAF [No. 25 Group RAF].

The airfield stayed under RAF control until 1982, when it was purchased by the current owners. Until 2007 it was the base of Thames Valley & Chiltern Air Ambulance helicopter.

Approximately 150 light aircraft are based at the airfield which, with three runways, is reportedly the largest grass airfield in civilian use in Europe. The airfield holds Civil Aviation Authority Public Use Aerodrome Licence Number P773, that allows flights for the public transport of passengers or for flight training.

The following units were also here at some point:

On 24 June 1989, the Fairey Hangar, on the north side of the airfield, was the venue for one of the largest acid house raves to be held at that time. The Sunrise Midsummer Party was attended by over 11,000 ravers, and attracted about 1,000 vehicles. This caused 3-mile (4.8 km) tailbacks on the approach to the airfield. The Sun newspaper ran a headline "Ecstasy Airport" the next day.

In October 2010, the airfield was turned into a 1950s London Heathrow Airport for the filming of the 2011 film My Week with Marilyn.

White Waltham Airfield also featured as the fictional Finchmere Airfield in the Midsomer Murders episode "The Flying Club", also using footage from the annual Retrofestival held at White Waltham.

The airfield plays a vital role as the hub for the Queens Flight in Nevil Shute's fiction " In the Wet" of 1953.

Many of the tasks in Series 11 of the Channel 4 programme Taskmaster took place at the airfield.

• Sturtivant, Ray; Hamlin, John (2007). Royal Air Force flying training and support units since 1912. Tonbridge, UK: Air-Britain (Historians). ISBN 978-0851-3036-59.
• Waltham - A Village at War 1939-45 by Dennis Tomlinson, ISBN 0-9534505-3-8
• 'White Waltham Impressions - Photographs Taken at the ATA Pageant on Saturday 29 September' in 'The Aeroplane Spotter', 18 October 1945

• West London Aero Club official site
• Multimap aerial photo