The March on London: Covert operations in the Battle of the Bulge -December 1944

Another aspect of the Germans’ thorough plans was the amazing scheme, somehow transmitted to Britain, for a break by all German prisoners of war. By all odds the most Wellsian phase of the German war of nerves, it has still not been completely explained. We do know that German prisoners began organizing for a mass break; that they plotted to seize arsenals, obtain tanks and actually prepare the way for German landings in England.
Captain Robert Merriam (official historian to the US Ninth Army in the Second World War)
No escape story of the Second World War was more daring in concept, more fantastic, more ambitious, more hopelessly fanatical than that of the prisoners of Devizes. It began with a bold master-plan for a mass break-out of German POWs from prison camps in wartime Britain.
Colonel Alexander Scotland (head of the British POW Interrogation Service in the Second World War)