'Scallywag Bunkers’: Geophysical Investigations of WW2 Auxiliary Unit Operational Bases (OBs) in the UK

In 1940, with the fall of France imminent, Britain prepared for invasion. After Dunkirk, with most armour and transport lost, a defence ‘stop line’ (GHQ Line) was prepared. Local Defence Volunteers (later Home Guard) were raised to buy time for the Home Army to deploy. Secret ‘Auxiliary Units’ were also formed, tasked with ‘Scallywagging’ – guerrilla activities ––in the invading army’s rear. 4-8 patrol men were highly skilled, often gamekeepers and poachers, with expert local area knowledge, with below-ground Operational Bases (OBs) in remote locations to avoid detection. No official records are released; but OBs were ‘Mark I’, enlarged deer setts, smuggler caves, etc., and Mark II, prefabricated designs by the Royal Engineers. This paper details three sites in Suffolk.
One unknown Mark I was destroyed, a Mark II was partially-intact and a Mark II was fully intact, all in secluded woods. Geophysical surveys found metal detectors optimal for location, with mid-frequency GPR/ERT optimal for characterisation. Archaeological finds included home-made braziers, 1940 kerosene heater stove, metal pans, ventilation systems and escape tunnels.
This study shows OBs varied in construction and condition, with surveys detecting and characterising them, bringing WWII British ‘invasion’ history into the wider scientific community and public domain.