Churchill's Secret Army Beneath the Welsh Countryside
- Jay Curtis
- 14 hours ago
- 5 min read
Few people realise that beneath our hills, woodlands and farmland lies the remains of one of Britain's most closely guarded wartime secrets.
During my latest exploration, I had the rare opportunity to step inside several of these hidden underground operational bases, a remarkable reminder of a plan so secret that many of the men involved took it to their graves. While I won't be revealing its exact location, the experience offered a fascinating glimpse into an extraordinary chapter of Welsh and British history that has remained hidden for decades.
Britain's Darkest Hour
The story begins in the summer of 1940. Although the British Expeditionary Force had escaped from Dunkirk in what became known as the "Miracle of Dunkirk", the troops returned home having abandoned most of their vehicles, heavy weapons and equipment on the beaches of France. Meanwhile, across the English Channel, Nazi Germany appeared unstoppable, and the threat of invasion seemed increasingly likely.
With Britain facing the possibility of occupation, Prime Minister Winston Churchill authorised the creation of one of the country's most secret organisations: The Auxiliary Units.
Unlike the Home Guard, these men were never intended to defend towns or beaches in open battle. Their war would only begin if Britain had already been invaded.
The Secret Army Hidden in Plain Sight
Around 3,500 volunteers were recruited from vulnerable coastal counties across Britain, including many patrols established throughout Wales.
The men were carefully selected from occupations that gave them exceptional knowledge of the local landscape. Farmers, agricultural workers, gamekeepers, foresters and even poachers were considered ideal recruits because they knew every woodland, hedgerow and hidden track in their area and could survive off the land if necessary.
Every volunteer signed the Official Secrets Act. Even husbands, wives, parents and close friends were never told the truth about what they were preparing for, with many families simply believed the men were carrying out routine Home Guard duties, never knowing they had volunteered for what was widely regarded as an almost certain suicide mission.
Life Underground
Each patrol usually consisted of five or six men and was assigned a concealed Operational Base, commonly known as an OB. Built deep underground and expertly camouflaged, these bunkers were almost impossible to spot from the surface. Some were constructed by Royal Engineers brought in from outside the local area to preserve secrecy, while others were built by the patrols themselves.
Inside were wooden bunks, food supplies, water, ammunition, explosives, storage areas, an Elsan chemical toilet and enough provisions to keep the patrol hidden for approximately two weeks. Legend even suggests many were stocked with a generous barrel of rum.
If German forces landed successfully, the patrol would disappear into its underground base and remain completely silent while enemy troops advanced overhead.
Only after the front line had moved on would they emerge, usually under the cover of darkness.
Britain's Hidden Resistance
The Auxiliary Units were trained to wage a ruthless guerrilla campaign behind enemy lines.
Their missions included destroying fuel depots, ammunition stores, railway lines, bridges and communication networks. They were also expected to sabotage transport routes, eliminate senior German officers and, if necessary, assassinate British collaborators who were believed to be assisting an occupying force.
The volunteers knew these operations would almost certainly end in death. Their operational bases were intended as temporary hideouts, but many understood that once their activities were discovered, the Germans would eventually locate the bunkers.
Few expected to survive for more than two weeks.
Training in Complete Secrecy
Training took place at Coleshill House in Oxfordshire, where the Auxiliary Units learned advanced guerrilla warfare, sabotage, demolition techniques, silent killing and the use of explosives.
They were often equipped with cutting-edge weapons before many frontline British soldiers received them. Even arriving for training was conducted in secret.
Volunteers travelled by train to Coleshill station before making their way to the village Post Office. There they gave a password to the local postmistress, Mabel Stranks, who would telephone Coleshill House. A vehicle would then collect them, deliberately taking an indirect route to ensure nobody could identify the location of the training centre.
Every stage of the operation was designed to leave as little trace as possible.
Secrets That Lasted a Lifetime
The level of secrecy surrounding the Auxiliary Units was astonishing.
Some patrols received sealed envelopes containing operational orders that were not to be opened unless invasion actually occurred. These reportedly contained details of local targets who would need to be eliminated once Britain was occupied. Anyone who knew the location of an Operational Base or possessed sensitive information could potentially become a target if there was a risk of that knowledge falling into enemy hands.
The secrecy also created personal hardships.
Because their work was hidden, some Auxiliary Unit members were wrongly accused of avoiding military service. A number were even presented with white feathers, a symbol used to shame men believed to be cowards. Bound by the Official Secrets Act which was valid for 50 years, they could say nothing in their own defence. Even after the war, many chose never to tell their families what they had really been preparing for.
An Overlooked Legacy
The skills developed within the Auxiliary Units proved invaluable, and several volunteers later transferred into Britain's emerging Special Forces, including the SAS, where some lost their lives during dangerous operations in occupied Europe.
When the invasion threat had finally passed, the Auxiliary Units were quietly stood down in late 1944. There were no campaign medals, no public celebrations and little official recognition. Unlike the Home Guard, these volunteers returned to ordinary civilian life without acknowledgement of the sacrifice they had been willing to make.
Meaningful public recognition did not arrive until 2013, when veterans and their families were finally invited to take part in the annual Remembrance Sunday march at the Cenotaph following years of campaigning by the Coleshill Auxiliary Research Team.
Discovering Britain's Forgotten Bunkers
Standing inside one of these hidden underground bases is a powerful reminder of just how close Britain believed invasion could become. Wales played its own important role in this secret network, with patrols and concealed bunkers established across the region, many of which remained completely unknown to local communities for decades.
Today, nature is slowly reclaiming these remarkable places. Yet historians believe that between 600 and 1,000 Operational Bases were constructed across Britain, and a significant number have still never been found.
That means some of the country's greatest wartime secrets may still lie hidden beneath our feet, waiting to be uncovered by someone walking the dog, exploring the countryside or even children stumbling across what appears to be nothing more than an overgrown hideaway.
If you'd like to see what it's really like inside one of these extraordinary underground bases, you can watch my full exploration in the video below. My visit only scratches the surface of this remarkable chapter of history. In the video, I take you inside one of these incredibly rare underground Operational Bases, explain how the Auxiliary Units were recruited and trained, reveal what life would have been like inside the bunker, and uncover the incredible story of the secret army that Churchill hoped would never have to fight.
Check out the full vlog!
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