The crash site of an early Battle of Britain Spitfire in a Kent field has been officially recorded for the first time in 86 years.

Spitfire N3201, which flew for the first time in November 1939, just over a year after the first of the aircraft was built, was shot down on July 20, 1940 and plummeted to the ground at Selsted, between Canterbury and Folkestone.

Spitfire pilots scramble at Biggin Hill during the Battle of Britain. Undated file pictureSpitfire pilots scramble at Biggin Hill during the Battle of Britain. Undated file pictureSpitfire pilots scramble at Biggin Hill during the Battle of Britain. Undated file picture

A three-day archaeological excavation has now discovered a significant quantity of debris, including aluminium alloy fragments and aircraft components carrying identifiable reference numbers.

Rather than simply recovering aircraft fragments, the purpose of the excavation was to investigate, record and understand the surviving evidence at the site.

Some of the pieces bear the “300” prefix associated with Spitfire components, with several appearing to have come from the aircraft’s wings.

The team also discovered .303 ammunition, including an unusual example dating back to 1926.

The dig was carried out by archaeologist Colin Welch and Research Resource Archaeology between August 21 and 23.

The precise location of the site had been kept secret during the project because of concerns about unwanted attention and night hawking.

Flight Officer Geoffrey Keighley was flying the Spitfire from 610 Squadron based at RAF Biggin Hill when its tail was shot out by a German Messerschmitt Me109 over Hawkinge.

Keighley was injured in one leg but managed to bale out of the aircraft and landed in Lydden but the aircraft hurtled to the ground and was destroyed.

He continued in the RAF throughout the rest of the war and was awarded an OBE in January 1945, before leaving the service as a Wing Commander in 1946. He died in April 1966 aged 53.

The recovered material from Keighley’s Mark 1a Spitfire – one of the first versions of the legendary aircraft – will now undergo further conservation and examination.

The first Spitfire entered service with the RAF in 1938 - the one in Selsted first flew in November 1939The first Spitfire entered service with the RAF in 1938 - the one in Selsted first flew in November 1939The first Spitfire entered service with the RAF in 1938 – the one in Selsted first flew in November 1939

It is hoped these tests could reveal more about the aircraft, where individual components originally came from and more information about the circumstances surrounding the site.

One of the most unusual discoveries came when a strong magnetometer reading led archaeologists to dig a 1.8m-deep trench.

Rather than strengthening, the signal weakened as they went deeper.

Further investigation found magnetic material scattered through the topsoil, apparently similar to the strip used in fridge-door seals.

It could be detected by magnetometers but not conventional metal detectors.

Flight Officer Geoffrey Keighley was flying the Spitfire from 610 Squadron based at RAF Biggin Hill. File picture supplied by Philip MacdougallFlight Officer Geoffrey Keighley was flying the Spitfire from 610 Squadron based at RAF Biggin Hill. File picture supplied by Philip MacdougallFlight Officer Geoffrey Keighley was flying the Spitfire from 610 Squadron based at RAF Biggin Hill. File picture supplied by Philip MacdougallArchaeologists are excavating the crash site of a shot-down early Spitfire from the Battle of Britain in a field in Selsted, near Folkestone and Canterbury. Picture: HE Services LtdArchaeologists are excavating the crash site of a shot-down early Spitfire from the Battle of Britain in a field in Selsted, near Folkestone and Canterbury. Picture: HE Services LtdArchaeologists are excavating the crash site of a shot-down early Spitfire from the Battle of Britain in a field in Selsted, near Folkestone and Canterbury. Picture: HE Services Ltd

The discovery has raised questions about a reported amateur excavation at the same location in the 1980s.

One theory is the material was deliberately placed as markers during the earlier dig, although this remains unconfirmed.

For Mr Welch, one of the most important outcomes of the latest investigation was that it created a formal archaeological record of the crash site for the first time.

He said: “It was such an incredible opportunity to be able to study a Battle of Britain early Spitfire and I am grateful, as always, that the HE Services team can see the virtue in the painstaking excavation with a machine that was perfect for the evaluation trench.

“The most important factor now is that there is a formal record of the site where there was not before.”

Rather than simply recovering aircraft fragments, the purpose of the excavation was to investigate, record and understand the surviving evidence at the site. Picture: HE Services LtdRather than simply recovering aircraft fragments, the purpose of the excavation was to investigate, record and understand the surviving evidence at the site. Picture: HE Services LtdRather than simply recovering aircraft fragments, the purpose of the excavation was to investigate, record and understand the surviving evidence at the site. Picture: HE Services Ltd

The excavation also used specialist GPS technology capable of recording the position of finds to approximately 1cm accuracy.

This allowed individual discoveries to be precisely plotted and used to create detailed digital plans for the archaeological report.

The system was particularly useful because the excavation area was on a significant slope, allowing the team to establish an accurately positioned reference area and relate the dig to drone-captured aerial imagery.

The excavation has now finished but research into the crash site is continuing.