As war broke out, he did more. His work took him to Trent Park in Barnet, Buckinghamshire’s Wilton Park and here to Latimer House. Working initially with a unit of British-born men fluent in German, and then with 101 Jewish refugees, Kendrick’s idea was cunningly simplistic: take in German prisoners of war, then bug the house to listen to their conversations. His gamble was that secrets would slip, skilfully upending the wartime adage of “Careless Talk Costs Lives”. Instead, he realised, it might save lives. By July 1942, Latimer House was his headquarters.