DIGGING started on Friday to uncover the Home Guard training school at Osterley House.
Archaeologists will attempt to reveal the Home Guard School No.1 as part of a 'Digging Dad's Army' project.
At the same time Osterley House and Park will celebrate of the 70th anniversary of the formation of the Home Guard by turning the 18th century site into a wartime camp.
Project leader Andy Brockman said: "Thankfully, Osterley Park has been protected from any kind of development because it was given to the National Trust immediately after the end of the war, so any underground remains of the training quarters should have survived fairly well."
The school was led by Tom Wintringham, a left-wing writer and former Spanish Civil War commander, and trainees were taught the theory and practice of modern warfare, from resisting an enemy invasion to house-to-house fighting.
Andy added: "There is much more to discover about a story so unlikely you just couldn't make it up.
"The oddest assortment of people, including guerrilla soldiers, surrealist painters, Russian spies, boy scout leaders and a lord of the realm came together with a plan to teach the public how to defend their country from a Nazi invasion during the most momentous period in British modern history - it's too fantastic for words."
Visitors can enjoy 'mini tours' of the excavation, study any 'finds', and on Sunday, assist the project's geophysics team.
Andy is also looking for help with research from members of the public and wants to hear from anyone who has stories or memorabilia linked to the Home Guard.
There is no charge to take part in the weekend, which runs from noon to 5pm each day.