Original Operational Base (OB)

The original Operational Base (OB), used for training during the war, still exists. It is situated within a 45 metre wide belt of trees surrounding the parkland. It was first "re-discovered" in 1996 by a small party from Ridgeway Military & Aviation Research Group after part of the roof had collapsed. In the images note the concrete cover over the OB main entrance, this is the view of the underside.It is showing the  impression of the wooden cover, that in turn would have been hidden beneath a camouflage. It is not clear whether this concrete was a later addition made after the facility was closed, to hide or make the entrance safe. The small arms rounds were found inside the OB.

It was linked to the Observation Post by telephone. Built to a standard design, it was replicated by engineers all around the country. The chimney from the OB came up inside a hollow tree so cooking fumes would emerge above the tree line. The hatch was opened by pulling on a cable hidden in a nearby bush.

The entrance shaft contained a metal ladder that led down to a narrow corridor with a brick built blast wall protecting it. A small alcove to the right would have housed the Elsan chemical toilet. Further on, on the left, is the site of the cooking stove and the vent pipe leading above ground through the hollowed out tree. The main chamber is made of an Elephant shelter. At the end of the chamber a small corridor led to an alcove on the right, thought to be a weapons and explosives store. The escape tunnel ran from the OB Southward and exited in the stone wall of the Ha-Ha. A pull switch opened the escape door. The roof of the escape tunnel has collapsed and now been cleared up and made into a new entranceway into the OB.

Close to the OB were a series of hatches over shallow pits, showing different ways to disguise the entrance to an OB. One was disguised as a tree stump and another lifted vertically with counterweights.

The original OB is now closed to the public due to it's frail state and the presence of roosting bates. The late Keith Blaxhall gave Harry Harris a tour in 2012.

In 2012 National Trust Volunteers built a replica Operational Base.

The replica OB was opened by Bath Auxilier Bob Millard.

Take a tour

Pictures
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Coleshill OB entrance shaft
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Coleshill OB looking up entrance
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Coleshill OB looking towards entrance
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Coleshill OB side chambers
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Coleshill OB showing contruction
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Coleshill OB main chamber
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Coleshill OB main chamber
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Coleshill OB bunk remains
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Coleshill OB looking down escape (now entrance)
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Coleshill OB escape (now entrance)
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Coleshill OB escape (now entrance)
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Coleshill OB escape (now entrance)
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Coleshill OB escape (now entrance)
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Coleshill OB escape (now entrance)
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Coleshill OB escape into Ha-Ha
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Coleshill OB chimney
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Coleshill Training OB main chamber 1996 (from RMARG)
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Coleshill OB 1996 excavating chimney (from RMARG)
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Coleshill OB 1996 entrance shaft. Note original hatch fixings (from RMARG)
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Coleshill OB 1996 concrete cover over the OB (from RMARG)
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National Trust Operational Base diagram
References

Ridgeway Military & Aviation Research Group

The National Trust