LYING just outside of Highworth, this palatial mansion kept one of the country’s most closely-guarded secrets during World War Two.

Thousands of men were trained at Coleshill House during the 1940s to form the backbone of a British resistance movement in the event that Hitler’s Nazis had successfully invaded the UK.

Now, thanks to a Heritage Lottery Fund grant of nearly £28,000, more people will have the chance to learn about the Auxiliary Unit, whose headquarters were at Coleshill House, which was destroyed in a fire shortly after the war.

The National Trust now manages and cares for the grounds where the Auxiliers received guerrilla training in survival skills, weaponry and sabotage techniques.

Over long weekends, small numbers of trainees would arrive to spend the next two days receiving instruction in explosives and unarmed combat. At night they were transported into the surrounding countryside and left to find their way back in the dark. An estimated 3000 men were trained here, who then went on to recruit others into the British resistance.

Highworth postmistress Mabel Stranks was key to the whole operation, becoming an essential part of Winston Churchill’s secret Auxiliary Unit from her position in the town’s High Street, where she security checked all trainees. For four years, from 1940 to 1944, she organised the training of more than 2,000 men at the secret location.

The funding will pay for the repair of the guard house and information displays for the public, as well as a replica underground operational base which will be constructed to ease visitor pressure on the original. This will be tied in with an enhanced education programme for schools.

The funding will also support the continuation of an oral history project to record the memories of the surviving Auxiliers and other local people which will be featured in the restored guard house.

The National Trust will be recruiting local volunteers to work with National Trust craftsmen on the building work and also help in running an expanded guided walks programme around the site.

Keith Blaxhall, who has been the National Trust warden at Coleshill for 31 years, has pioneered the project, along with Liza Dibble, education officer for the Buscot and Coleshill Estates, having spent years researching the subject.

“I am delighted that the story of Coleshill and its secret underground army will now be unearthed for a new generation of people to discover and enjoy,” said Keith. “We are most grateful to those who have already shared their stories with us, and we look forward to hearing more.”

Author John Warwicker, who has written two books on the Auxiliary Units, added: “Not only was Coleshill the training centre for secret warfare, but also the site for the manufacture of a very secret two-way radio transceiver and, it seems certain, involved in training Special Forces for one-off behind the lines engagement. There is still much to discover.”