From Secret Airfield to Museum: The Story of RAF Defford
Nestled within the tranquil landscape of Croome Court in Worcestershire lies a remarkable history, one that played a pivotal role in shaping the outcome of World War II and the subsequent Cold War. What appears today as a serene National Trust property was once the clandestine home of RAF Defford, a top-secret airfield that became Britain's leading center for the development of airborne radar technology.
The story of RAF Defford began in 1940, as the shadow of war loomed large over Britain. A significant portion of the land at Croome Court, then owned by the Earl of Coventry, was requisitioned to establish a vital military installation. This transformation saw swathes of parkland converted into an airfield, with numerous structures rapidly erected to support the war effort. Airfield facilities, accommodation for service personnel, a medical wing, an ambulance garage, and even a mortuary sprang up across the site. Initially operational in September 1941, RAF Defford first served as a training base for Vickers Wellington bombers.
However, the airfield's destiny took a significant turn in May 1942 with the relocation of the Telecommunications Research Establishment (TRE) and its flying unit to the area. The responsible for groundbreaking radar research and development, moved inland to Malvern College for safety reasons, and its flight testing arm, the Telecommunications Flying Unit (TFU), later renamed the Radar Research Flying Unit (RRFU), transferred its aircraft to the nearby Defford airfield. This strategic move positioned RAF Defford at the forefront of airborne radar innovation.
From this unassuming location, civilian scientists and aircrews from the Royal Air Force and Royal Navy collaborated to develop and test radar systems that would revolutionize Allied aircraft capabilities. Early triumphs included Airborne Interception (AI) systems, which dramatically improved the effectiveness of night fighter aircraft, enabling pilots like John "Cats Eyes" Cunningham to successfully intercept enemy bombers. Another crucial development was the Air to Surface Vessel (ASV) radar, which became operational in 1943 and proved instrumental in the Battle of the Atlantic by allowing Allied aircraft to detect and counter the threat of German U-boats. This technology could even spot small parts of submerged submarines, such as periscopes and snorkels.
RAF Defford was central to H2S development from 1942 when TRE and TFU moved up from Dorset. A ground-scanning system that significantly enhanced the accuracy of navigation and target identification for Bomber Command crews engaged in the strategic bombing of Nazi Germany. The ground-mapping capability of H2S was discovered a controlled experiment during tests at Defford. This system, spearheaded by scientists like Bernard Lovell, relied on an advanced version of the cavity magnetron. Additionally, the Monica tail-warning radar was developed to provide bomber crews with early alerts of approaching enemy aircraft. Trials of this system were conducted from Defford by personnel like Audrey Rundle of the Women's Auxiliary Air Force (WAAF).
RAF Defford's pioneering spirit extended beyond these key systems. A converted Wellington bomber based at the airfield served as a forerunner of the modern AWACS aircraft, successfully detecting fast-moving German E-boats and directing Allied aircraft to intercept them. In a remarkable feat of engineering, the world's first automatic "hands off" approach and landing system was achieved by a Boeing 247 aircraft at Defford in January 1945, utilizing Rebecca and Babs technology. The shift towards shorter "centimetric" wavelengths for radar, around 10cm, was another critical advancement made at TRE's Defford facility, leading to higher resolution and more accurate airborne radar maps.
The groundbreaking work at RAF Defford was made possible by the dedication of numerous individuals, including Bernard Lovell, who was in charge of H2S deveoplment collaborating closely with eleven colleagues who lost their lives in June 1942 during an H2S test flight from Defford, when the Halifax bomber crash while testing the crucial radar technology.
The contributions of women at RAF Defford were also significant, with approximately 600 women employed at the site during the war, many in technical roles. One notable example is the mother of Tim Berners-Lee, the inventor of the internet. The RAF Defford Museum features an exhibition, "Women of RAF Defford – Heroines of Croome at War," highlighting their vital contributions as scientists, technicians, and in other essential roles. Audrey Rundle, a WAAF medical radiologist, flew on trials of the "Monica" tail-warning radar from Defford. Wrens (Women's Royal Naval Service) also served as expert radar operators in Fleet Air Arm aircraft based at the airfield.
The impact of the radar development at RAF Defford on the Allied victory in World War II cannot be overstated . The technologies developed at this secret airfield were crucial in the Battle of the Atlantic, enabling the detection of German U-boats that threatened to cripple Britain's supply lines. Airborne radar also allowed for more accurate nighttime bombing raids. Furthermore, personnel at RAF Defford pioneered systems for jamming and spoofing German communications, laying the groundwork for modern electronic warfare. The "Window" (chaff) radio countermeasure system, invented by Joan Curran and tested at Defford, proved highly effective in reducing bomber losses.
Following the Second World War, RAF Defford continued its secret work during the Cold War . It remained a key center for the development and testing of airborne radar technology . The first jet aircraft to land at Defford was a Gloster Meteor in September 1945. However, by September 1957, all flying operations were moved to nearby RAF Pershore as the runways at Defford were too short for the larger jet bombers entering service. Despite the end of flying, Defford remained scientifically significant, becoming a base for radio astronomy. In 1980, the former Signals Research and Development Establishment relocated to Defford, becoming a Royal Signals and Radar Establishment (RSRE) facility involved in the design and testing of Skynet military communications satellites.
The legacy of RAF Defford is preserved and promoted by the Defford Airfield Heritage Group (DAHG), formed in 2010 . Evolving from the RAF Defford Reunion Association, DAHG is dedicated to researching, documenting, preserving, and promoting the history of the airfield . In partnership with the National Trust, DAHG was instrumental in establishing the RAF Defford Museum, which opened in September 2014 in the restored decontamination annexe of the former medical wing . By the end of 2019, the museum had welcomed over 300,000 visitors.
The RAF Defford Museum offers a fascinating glimpse into this secret history. Exhibits include a 1951 b2 bomber Canberra, WD956, the museum also features the "Women of RAF Defford" exhibition , displays on Defford's role during the Cold War , and various artifacts and historical information .
The RAF Defford Museum is located at the National Trust property Croome, near Worcester . It is open seven days a week from 11:00 to 16:00, all year round. Admission to the museum is included with entry to Croome Park, which is free for National Trust members; non-members will need to pay an entry fee . Croome is situated approximately 9 miles south of Worcester and is easily accessible from the M5 motorway (Junction 7) and is signposted from the A38 and B4084 . For those using public transport, Aston's bus route 382 from Worcester to Pershore stops near Croome, as does route 362 from Worcester to Upton/Malvern, both requiring a 2-mile walk . The nearest train station is Pershore, about 7 miles away.
RAF Defford's history is filled with significant events and anecdotes . The tragic crash of Halifax V9977 in 1942, which claimed the lives of Alan Blumlein and ten others, remains a poignant reminder of the risks involved in pioneering research. The world's first automatic landing in 1945 showcased the advanced technology being developed. Even a forced landing of a Spitfire in 1945 adds to the airfield's rich tapestry of stories. Today, visitors can explore the museum, walk the grounds, and even participate in guided history walks to learn more about this extraordinary site and its vital contributions to aviation and wartime technology .
The story of RAF Defford is a testament to the ingenuity, collaboration, and sacrifice that took place during a critical period in history, which is kept alive by a team of Volunteers who are on hand to tell the various stories known . From its secret wartime operations to its continued scientific contributions during the Cold War, and now as a museum preserving its legacy, RAF Defford remains a site of profound historical importance. A visit to the RAF Defford Museum at Croome offers a unique opportunity to uncover the secrets of this once-clandestine airfield and appreciate its vital role in shaping the modern world.
My late father, originally from London, was transferred to RAF Defford in 1944 when he was aged 21, from 198 Typhon Squadron, at Manston. He married my late mother a Worcester native which his marriage banns took place in Croome Church, he settled in the area after the war. He frequently spoke of his time in the Royal Air Force, recalling both sadness of losing colleagues on combat missions, and the unique, secretive nature of the work at Defford. He often remarked that, due to the base's classified operations, personnel tended to remain there once assigned.
WPP Research completed by Pam Hinks 14.04.2025
RAF Defford Museum at Croome National Trust https://www.nationaltrust.org.uk/visit/worcestershire-herefordshire/croome/raf-defford-museum
F/Sgt Norman Dolbear SRU 1942-46 (From the records of the late C.R.Rouse)
Bernard Lovell
Leading Scientist
University of Bristol/Manchester
Key figure in the development of H2S radar, led the development of a blind bombing system.
Alan Blumlein
Electronics Engineer
EMI
Key figure in the development of H2S radar, pioneer in electronics and telecommunications.
Ronald John Denham (Sansom)
Squadron Leader, Liaison Officer
RAF
Liaison for the Technical Flying Unit, involved in H2S testing, senior officer on fatal Halifax flight.
Geoff Hensby
Science-Observer, Honorary Flying Officer
RAF
Involved in H2S testing, perished in the Halifax crash.
Cecil Browne
Civilian Science-Observer
EMI
Involved in H2S testing, perished in the Halifax crash.
Frank Blythen
Civilian Science-Observer
EMI
Involved in H2S testing, perished in the Halifax crash.
Audrey Rundle
Medical Radiologist, Women's Auxiliary Air Force (WAAF)
WAAF
Flew from Defford on trials of the "Monica" tail-warning radar.
Airborne Radar Types Developed/Tested at RAF Defford During WWII
Radar System Name
Primary Function/Purpose
Key Features/Technologies
Operational Significance
Airborne Interception (AI)
Detecting and tracking enemy aircraft at night
Early radar systems for night fighters
Significantly improved RAF's ability to counter nighttime bombing raids.
Air to Surface Vessel (ASV)
Detecting surfaced and partially submerged submarines
Centimetric wavelengths, improved definition
Crucial in the Battle of the Atlantic, enabling detection of U-boats and securing Allied supply lines.
H2S
Accurate navigation and target identification for bombers
Ground-scanning radar, 10cm wavelength, cavity magnetron
Greatly enhanced bombing accuracy, reduced civilian casualties, improved strategic bombing effectiveness.
Monica
Warning bomber crews of approaching enemy aircraft from the rear
Tail-warning radar
Increased survivability of bomber crews by providing early warning of attacks.
Forerunner of AWACS
Early warning and control of aircraft
Radar mounted on a Wellington bomber
Demonstrated the potential of airborne early warning and control systems.
Automatic "hands off" landing
Automatic approach and landing of aircraft
Rebecca and Babs (beam approach beacon system), likely radar
Pioneering work in aviation safety and all-weather operations.
The story of RAF Defford is a testament to the ingenuity, collaboration, and sacrifice that took place during a critical period in history, which is kept alive by a team of Volunteers who are on hand to tell the various stories known . From its secret wartime operations to its continued scientific contributions during the Cold War, and now as a museum preserving its legacy, RAF Defford remains a site of profound historical importance. A visit to the RAF Defford Museum at Croome offers a unique opportunity to uncover the secrets of this once-clandestine airfield and appreciate its vital role in shaping the modern world.
My late father, originally from London, was transferred to RAF Defford in 1944 when he was aged 21, from 198 Typhon Squadron, at Manston. He married my late mother a Worcester native which his marriage banns took place in Croome Church, he settled in the area after the war. He frequently spoke of his time in the Royal Air Force, recalling both sadness of losing colleagues on combat missions, and the unique, secretive nature of the work at Defford. He often remarked that, due to the base's classified operations, personnel tended to remain there once assigned.
(From the records of the late C.R.Rouse)
WPP Research completed by Pam Hinks 14.04.2025
RAF Defford Museum at Croome National Trust https://www.nationaltrust.org.uk/visit/worcestershire-herefordshire/croome/raf-defford-museum