Archaeologists are surveying the remains of Winston Churchill's secret headquarters in the hope of uncovering a new underground operations base.

The Coleshill estate was the English headquarters of a highly trained guerrilla volunteer force during World War II.

The house and its grounds, on the Oxfordshire/Wiltshire border, are now owned by the National Trust.

The survey has been organised by the Coleshill Auxiliary Research Team.

The team was set up by Tom Sykes to research, document and preserve the history of the guerrilla volunteer force, known as auxiliary units....