When war came in 1939 the aerodrome became RAF Sywell, a training airfield where No. 6 Elementary Flying Training School and other units taught new pilots on de Havilland Tiger Moths. Among the men who soloed here were Pierre Clostermann, the French Free Air Force ace who would write the wartime memoir 'The Big Show,' and Paddy Finucane, the young Irish-born Spitfire pilot who would die at twenty-one over the Channel after ground-based machine-gun fire punctured his radiator during a fighter sweep. Sywell did more than train. From 1942 to 1943 the workshops at the field, run by Wallis Industries, assembled close to a hundred Avro Lancasters, the heavy four-engined bombers that would form the spine of Bomber Command's night offensive. The Wellington repair shop here became one of the largest in the country, returning damaged Vickers Wellington bombers to operational squadrons. The long brick sheds where that work happened are still standing on the site. Aerial sequences for the 1969 film Battle of Britain were shot over Sywell, with the Spanish-built Hispano Buchons standing in for Messerschmitts.

For most of its history Sywell operated on grass alone, which is romantic in dry weather and impossible in winter when the strips waterlog. In 1999 the management applied for permission to build a concrete all-weather runway. Two campaign groups formed in opposition: STARE (Stop The Aerodrome Runway Expansion) and the local branch of CPRE, the Campaign to Protect Rural England. Their argument was about quiet country and the slow expansion of aircraft size and traffic. The Department for Transport approved the runway on 22 November 2007 and construction began in 2008. The 1,000-metre concrete strip opened in summer 2009. It is short by airline standards and cannot take passenger jets; what it has done is let the aerodrome stay open through winter and add night training. The political question of how rural an airfield in rural England gets to remain has not really gone away.

Sywell now hosts something like 138 businesses on its industrial park, but the ones that stop visitors in the viewing area are the aviation tenants. Air Leasing Ltd moved in during January 2016 and now occupies three hangars, one of them locally nicknamed Graceland for the Spitfire that anchors the workshop: Supermarine Spitfire TR.9 ML407 'OU-V,' known as the Grace Spitfire. Beside it sit Hurricanes, P-51 Mustangs, a Sea Fury. Air Leasing's subsidiary Ultimate Warbird Flights takes paying passengers up for trial experience flights in two-seat warbirds. The Blades aerobatic team based their five Extra EA-300s here until they disbanded after seventeen seasons in 2022. 2Excel, the Blades' parent company, still operates from the field with a fleet ranging from a Beech King Air to a modified Boeing 727 used for oil spill response. Sloane Helicopters handles Robinson and Leonardo rotorcraft. Flylight Airsports trains and sells microlights. Cabaero teaches fixed-wing students on a fleet that includes a couple of Aero AT-3s and a Piper Cherokee.

Sywell hosts a thick calendar of events. The 'Pistons and Props' classic motor and aviation show in September pulls thousands; the Light Aircraft Association Rally found a home here from 2009 onwards after stints at Cranfield and Kemble. The Sywell Airshow was a major bi-ennial charity event from 2004 to 2014, then paused after the 2015 Shoreham crash led to tighter air display rules, then resumed briefly in 2024, then was effectively shelved after the death of principal organiser Richard Grace later that year. Quieter heroes pass through too. The Handley Page Jetstream 200, registration G-RAVL, was built at Sywell in 1969 by the Sywell-based Jetstream Ltd company and won the Daily Express National Air Race on 12 June 1971 in a televised run from Sywell to Biggin Hill. The aircraft returned to Sywell in March 2021 to be restored by the Aviation Museum next door as a classroom and exhibit, completing the long circle home.

Calling Sywell on 122.705 inbound, you are answered by an AFIS officer rather than air traffic control, the difference being that he gives you traffic information rather than orders. Prior permission is required for non-based aircraft, which means a phone call before you set out. The Cat 1 fire service stands by during operating hours with Land Rover and Dodge Ram appliances. Jet A1, AVGAS 100LL, and MOGAS are all on the field. The Pilots' Mess cafe sits next to the tower; the Aviator Hotel on the south side has a restaurant and fifty rooms in two Art Deco-styled blocks. After shutdown you can walk past the airfield memorial in the spotters' area, where a small marker honours the men who trained at RAF Sywell and did not come home, then watch the sun set behind the Wellington sheds, which is exactly the right way to end any visit.