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. Though it is uncertain if it received its 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 produced for Berkshire County Council in 1995 but remained absent from the West Berkshire Historic Environment Record (HER) 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 (BEF) along the French coastline. A series of daring rescue operations successfully evacuated hundreds of thousands of stranded Allied servicemen. But Britain now faced the frightening prospect of a full-scale seaborne invasion, coinciding with the Luftwaffe gaining air supremacy over her skies. On July 16, Hitler issued Directive 16 outlining plans for an amphibious landing on British shores by September, codenamed 'Operation Sealion'.
The War Cabinet tasked General Sir Edmund Ironside, Chairman of the newly formed Home Defence Executive and Commander-in-Chief of the Home Forces since May 27, with securing Britain's anti-invasion defences. He succeeded General Sir Walter Kirke, whom he called a "poor chap...hampered by people not taking the defence of England more seriously." Whereas now, invasion hysteria had consumed the entire nation.
Britain could rebuild its fragile military by calling reserves, conscription, voluntary recruitment and troops withdrawn from India. But replacing the thousands of tons of ammunition, guns and vehicles 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 respond. Under no circumstances could the Nazis rampage through Britain as they had in Northern France and the Low Countries.
The proposed General Headquarters Line (GHQ Line) spanned almost 800 miles from Bristol to London and up to Edinburgh. More than 50 smaller corps and divisional stop lines also existed. Ironside's Chief of Staff, General Bernard Paget, presented his strategy to the War Cabinet on June 25 as Home Forces Operation Instruction No. 3. Once they approved it, 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 prioritize all civilian labour towards building defences. "All local contractors and workmen must be taken off useless frills and put to this defence," Ironside wrote in a revealing letter to Lieutenant General Sir Bertie Fisher, General Officer Commanding-in-Chief for 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 continuing 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.
Pillbox Construction
Pillboxes followed several standard designs issued by the Directorate of Fortifications and Works (FW3), set up at the War Office under Major-General GBO Taylor. Royal Engineers and civilian contractors oversaw their construction — including the building arm of Camp Hopson in Newbury. Canal boats transported the building materials.
Workers poured concrete into wooden or brick shuttering, sometimes left intact where concrete supplies were low. This would help create the illusion that the entire structure was made of brick. Metal rods and plating reinforced the walls and ceiling, more visible as their outer concrete shells crumble away. Common features include bullet-proof walls and narrow loopholes for light infantry pillboxes, designed for rifle fire. Whereas artillery pillboxes have thicker, shell-proof walls, Bren or Vickers light machine gun chambers and wide embrasures to accommodate anti-tank guns. These could withstand heavy bombardment.
Local variations soon appeared owing to each region's strategic needs and resource availability. Some pillboxes 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 using horizontal plank shuttering in Pangbourne.
Evolution of Home Defence
The Local Defence Volunteers (LDV) was formed in May 1940 by Secretary of State for War, Anthony Eden, and General Kirke, its forgotten architect. It was later renamed the Home Guard by Churchill in a BBC broadcast. Its members surpassed one million by July, mainly men but later women as well. The Home Guard was initially regarded as an ill-disciplined 'broomstick' army, wielding Molotov cocktails and improvised flamethrowers. But a supply of 500,000 rifles and automatic weapons from America helped bolster its arsenal and shape it into a professional force.
It 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. Though managed by Central and Local Commanders, the whole organization reported to Ironside. Troops were spread thin throughout the country, for Ironside never knew for certain where the enemy might land.
The GHQ Auxiliaries, sometimes erroneously called the 'British Resistance Organization', consisted of a top-secret guerilla army — the War Cabinet's answer to the German 'stormtroopers'. Small resistance cells would hide in underground operational bases armed with Tommy guns and would activate if Britain ever became occupied, sabotaging enemy supply lines and executing collaborators. It recruited from the toughest and most able ranks of the Home Guard and was eventually incorporated into the Army and later the SAS, seeing combat overseas.
General Ironside has often been criticized for his outdated 'siege mentality'. The War Cabinet replaced him with General Sir Alan Brooke on July 19, 1940 after serving just two months in the role. But static defence only formed one part of Ironside's strategy. His war diaries reveal an insight into his rationale. On June 8, he wrote: "There must be no question of cowering behind an obstacle, waiting to be attacked. The enemy must be located instantly, isolated, and attacked before he can gather strength." He also criticized the French for investing so heavily in the Maginot Line rather than in developing their mobile columns and aviation.
The other forgotten part of Ironside's strategy involved deploying centrally placed mobile and armoured reserves to reinforce any areas of the country under threat. Smaller mobile units would respond to landing enemy parachutists at a local level. Ironside recognized the value of static defence lay in delaying an enemy offensive, not preventing it. He worked to reorganize six regiments of the BEF into highly mobile mechanized cavalry. He developed up to 700 special armoured cars called 'Ironsides', each mounting a Bren gun. Armoured lorries would transport supporting infantry where required.
As more and more troops and resources became available, the Field Army could be released from guarding static defences to pursue a more mobile role. But unfortunately, progress did not occur quickly enough for Ironside.
The War Cabinet did not state the reason for his removal. Nor did General Brooke's diary entry written after his meeting with Eden later the same day. But Ironside's diary paints a different picture. He writes he was summoned to see Eden at 2:45pm, who told him "the Cabinet wished to have someone with late experience of the war." Brooke had first-hand experience fighting and coordinating the Allied evacuation from France, so the reason stated is plausible.
The fact remains that Germany had been rearming since the early 1930s and had tried and tested its Blitzkrieg ('lightning war') strategy with terrifying success in Poland and later in Western Europe. Under the circumstances, Ironside prepared the best he could with such limited time and resources.
General Brooke and Churchill both appeared to favour a more offensive approach. 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. He directed the dwindling supplies of cement to strengthen these areas. Nodal points 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'. In 1939, the town had only one main north-south route via Northbrook Street. The 'Emergency Bridge' was built sometime between July 1940 and February 1941 to connect Park Way and The Wharf amid growing concerns the town would become divided if enemy bombers destroyed Newbury Bridge.
The town 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. Demolition belts were a common last resort.
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. A rare example of a twin Type 28 anti-tank gun emplacement survives at Dunmill Lock. These pillboxes could take a two-pounder anti-tank gun.
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. Others were destroyed by weapons testing ahead of D-Day. More permanent structures, like pillboxes, were often left in situ since demolishing them demanded too much labour, hence why Thatcham's gunpit survives today.
Berkshire County Council contracted Ashampstead civil engineering firm, LJ Dixon, to remove defence works throughout the Hungerford and Thatcham Districts in March and May 1945, costing £1,242 in total.
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 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.
Please contact archaeology@westberks.gov.uk to report, save and record a historic discovery.