LONDON — It was certainly not what the captured Nazi generals expected — or deserved. As historian Helen Fry describes in her new book, “The Walls Have Ears: The Greatest Intelligence Operation of World War II,” Trent Park, the stately country house in north London to which the prisoners were confined, rather resembled a gentleman’s club. The most senior generals had their own rooms, with adjoining sitting rooms. There was a room for playing billiards, table-tennis and cards. And, after afternoon tea on Christmas Eve, a festive dinner was laid out for them. There was even an appropriately deferential welcome...
