New discovery at Thatcham echoes West Berkshire's last stand against the Nazis
A local resident contacted Thatcham Town Council's Heritage Working Party earlier this year regarding their re-discovery of a hexagonal concrete gun emplacement, designed to mount either a light machine gun or six-pounder anti-tank gun. The concrete base remains are located between the canal bridge and level crossing at Thatcham Railway Station.
The structure is listed in the Defence of Britain archive and the Bastions of Berkshire booklet, but remained absent from the West Berkshire Historic Environment Record until recently. It is visible in RAF aerial photography from 1946 but is not marked on the 1961 Ordnance Survey and is obscured by undergrowth on Google Earth by 2003.
However, Thatcham's ruin is only a small part of a much larger story.
GHQ Main Line
By May 1940, the Nazis had trapped the retreating British Expeditionary Force along the French coastline. A series of daring rescue operations successfully evacuated hundreds of thousands of stranded Allied servicemen.
But Britain now faced the alarming prospect of a full-scale seaborne invasion, coinciding with the Luftwaffe gaining air supremacy over her skies. On July 16, Hitler announced plans to invade Britain by September, codenamed 'Operation Sealion'.
The War Cabinet tasked the new commander-in-chief of the Home Forces, general sir Edmund Ironside, with securing Britain's anti-invasion defences.
Britain could rebuild its fragile military by calling reserves, conscription and voluntary recruitment. But replacing the thousands of vehicles and ordnance it had lost at Dunkirk remained a pressing concern.
To overcome these challenges, Ironside envisioned a wide network of coastal and inland defensive stop lines enclosing London and the industrial Midlands, including the Blue Line in West Berkshire. These would delay, but not prevent, an enemy offensive, allowing enough time for mobile reserves to react.
Under no circumstances could the Nazis rampage through Britain as they had in Northern France and the Low Countries.
The proposed General Headquarters Line spanned almost 800 miles from Bristol to London and up to Edinburgh.
The War Cabinet approved Ironside's strategy on June 25 and the Royal Engineers Field Company immediately began surveying the nation for strategic vulnerabilities.
Ironside then ordered the most intense period of military construction Britain had seen for centuries. He wrote to his regional commissioners, urging them to instruct their town and borough councils to prioritise all civilian labour towards building defences. "All local contractors and workmen must be taken off useless frills and put to this defence," Ironside stated in a revealing letter to Southern Command.
Workers dug thousands of miles of anti-tank trenches and constructed almost 20,000 pillboxes in the first 16 weeks — as the Battle of Britain raged above.
Wherever possible, defences exploited natural and artificial features such as rivers, canals and bridges the enemy might use to advance further inland.
GHQ Line Blue
The Blue Line followed the River Kennet and Kennet and Avon Canal from Melksham to Reading. The Red Line joined the River Thames at Reading and continued up through the Sulham Valley to Pangbourne before going towards Abingdon.
Not all pillboxes appear on the Blue Line. Some guarded airfields and other military installations instead.
Woolhampton's pillboxes protected a bridgehead to allow counter-attacking forces unhindered access across the canal.
Royal Engineers and civilian contractors — including the building arm of Camp Hopson in Newbury — constructed bullet-proof and shell-proof infantry and artillery pillboxes based on standard War Office designs. Canal boats transported the building materials.
Some were painted, covered with camouflaged netting, buried under earthworks or disguised as other buildings to conceal their true purpose.
Examples include a derelict cottage converted into a secret fortification at Widmead Lock in Thatcham; a Type 26 pillbox posing as a shed in Ufton Nervet and a Type 22 pillbox built with horizontal plank shuttering in Pangbourne.
Evolution of Home Defence
The Local Defence Volunteers, later renamed the Home Guard by Churchill, formed in May 1940. Its members surpassed one million by July and played an active role in patrolling Britain's defences alongside the Regular Army, Territorials and GHQ Auxiliaries — a far cry from its stereotypical 'Dad's Army' depiction.
The War Cabinet replaced Ironside with general sir Alan Brooke on July 19, 1940 after serving just two months in the role.
General Brooke continued building static defences, albeit with a greater emphasis on reinforcing Britain's 'coastal crust' and 'nodal points', also called 'fortress towns' or 'anti-tank islands' — strategic strongpoints where the roads and rivers converged. These were classed as either Category A, B or C depending on how long they were expected to hold out under attack. West Berkshire had two.
Newbury is marked as an anti-tank island on the map of the 'Southern Command Home Defence Programme 1940'. It was reclassified as a Category B anti-tank island in 1941, defended by the Home Guard.
Northbrook Street had a six-pounder gunpit. Other defences included around nine pillboxes, concrete roadblocks, vertical iron rails and dragon's teeth. Explosives were supposedly planted beneath the butcher's shop — now a Costa Coffee — to destroy Newbury Bridge if it became overrun.
Hungerford was also reclassified as a Category C anti-tank island in 1941, defended by the Home Guard. Its defences included a six-pounder gunpit in the High Street, concrete roadblocks, dragon's teeth, hedgehogs and at least a dozen pillboxes.
Post-War
The decisive outcome of the Battle of Britain and Germany's invasion of the Soviet Union in 1941 reduced the demand for anti-invasion defences. Not all were completed.
Some 6,000 pillboxes survive nationwide today, with 150 in Berkshire. Many have been demolished or eroded away.
More permanent structures, like pillboxes, were often left in situ as demolishing them demanded too much labour, hence why Thatcham's gunpit survives today.
Berkshire County Council contracted an Ashampstead civil engineering firm to remove defence works throughout the Hungerford and Thatcham Districts in March and May 1945.
Workers demolished the two gunpits and removed dozens of dragon's teeth and concrete obstructions from Hungerford High Street, Hungerford Common, Eddington, Hamstead Mill, Oakhill, Hungerford, Kintbury, Hamstead Marshall, Speen, Reading, Burghfield, Aldermaston, Ufton Green and south of Thatcham Station.
The result is a partial representation of how effective static defences could have been in repelling an invasion.
Watch the documentary Britain's Forgotten Frontier at https://youtu.be/yobhVR5IN1s to discover more about how Thatcham's gunpit supported the town's wider defence network.
And visit https://youtu.be/3FgvA0Sk7nI to hear a leading expert on wartime defences explain the mythology and evolution of Britain's Home Defence.
Always seek landowner permission before conducting any fieldwork on private or council land.
Please contact archaeology@westberks.gov.uk to report, save and record a historic discovery