A secret military training site near Swindon, used during the Second World War, opened to the public for the first time at the weekend.

The Coleshill House estate, near Highworth, was one of many of its kind across the country used by secret guerilla factions of the British Army, called the Auxiliary Units, in the 1940s to train in espionage techniques.

The National Trust opened the estate to the public on Sunday to mark the 70th anniversary of the formation of the Auxiliary Units following the evacuation from Dunkirk.

They were also known as Churchill’s underground army.

The event included talks from military historians and former Auxiliers, as well as a tour around an underground operational base and various re-enactments.

The National Trust has also been awarded £30,000 from the Lottery Fund to restore the site, including building a replica operational base, so it can open to the public on a regular basis.

Liza Dibble, the community learning officer for the trust, organised the event.

She said: “I have been delighted, far more people than we thought have come along.

“We are hoping to use this event as a platform because we have lottery funding to make it a permanent interpretation.”

Bill King, a military historian who gave a lecture on the history of the Auxiliary Units on the day, said it was important sites like Coleshill were recognised.

He said: “I’m really pleased with the turn-out.

The talks have been extremely well attended.”