Coleshill House was the training headquarters for the Auxiliary Units - the ‘stay behind’ force who would have conducted sabotage and reconnaissance behind enemy lines in World War II in the event of a German invasion. Members attending training at the site were dropped in nearby Highworth and taken to Coleshill in the back of covered lorries to help maintain its secrecy.
The house was back in private hands by 1946 and sold to Ernest Cook, of the famous Thomas Cook travel agent family, During renovations in 1952 the house caught fire and it was completely destroyed. The estate was gifted to the National Trust shortly thereafter.
The grounds contain a training OB (Operational Base) which would have been used by a team of six men from which to launch their attacks. Alongside this OB are a series of other pits, in which alternative concealment methods for the entrance were demonstrated. These included concealment by tree stumps and counter-balanced trays.
Elsewhere on the estate are other remains including hut bases, a vehicle ramp and a likely Observation Post (OP) and explosives cache. Recognising the importance of this period in its history, the National Trust also built a replica OB in the early 21st century.
Both the (original) training OB and its modern replica can be visited on organised tours.