Journalist Tina Rosenberg is best known for her book The Haunted Land: Facing Europe’s Ghosts After Communism, which received both a Pulitzer Prize and the National Book Award, and for her prolific editorial writing for the New York Times. Her latest single, D For Deception (Atavist), is the fascinating real-life story of Britain’s prewar master spy novelist, Dennis Wheatley, and the vital role he played in outwitting German intelligence during World War II. I put six questions to her about Wheatley and his work:

1. How did you come across Dennis Wheatley, and what gave you the idea to write a book about him?

In February while in London, I visited the Churchill War Rooms — the underground bunker Churchill used during the war. (The bunker in Skyfall that purports to be Churchill’s is fake.) It’s a fascinating museum, and what interested me most there was a picture of Dennis Wheatley, with this caption: “A popular thriller writer, Wheatley drew on his imagination to produce cover plans for Allied operations. His work included a plan, code named ‘Bodyguard,’ to deceive the Germans about the place and date of the Allied ‘D-Day’ invasion of Europe.”

Like everyone who reads spy novels, I knew about the great British tradition of spies putting what they have lived to literary profit — John Buchan, Graham Greene, John Le Carré, and Somerset Maugham were all spies first, writers of espionage novels later. But Wheatley did it the other way around. I was fascinated by the idea that someone could invent deceptions for a fictional character and then use this skill to fool Hitler.

2. In what sense was Wheatley’s life a “double deception”?

Wheatley carried out deceptions on two levels: in his books, and in real life. His real-life deception work was unprecedented. Tactical deception is as old as battle, of course. What was new was the idea of investing in lies for the long term.

For example, Operation Bodyguard (despite what the photo caption says, Wheatley was one of many people who worked on it) aimed to make Hitler believe that the invasion of Normandy was itself only a feint — that the real invasion, with a million men, would come later at Pas de Calais. That’s how Britain kept Hitler from moving his troops away from Pas de Calais to Normandy. Even after the Allied expedition landed in Normandy and began fighting its way south, it took Hitler over seven weeks to start moving his forces from Pas de Calais, because he was still waiting for the “real” invasion.

Why did Hitler fall for this deception? Because the deceivers had spent years inducing him to wildly overestimate Allied troop strength. The week before D-Day, Hitler thought the Allies could command more than eighty divisions in Britain. In truth, there were only fifty-two.

Deception worked like this: First, Wheatley and his colleagues drew up a cover story (“story” is actually the term of art) for each operation — what they wanted Hitler to believe. Then they began to scatter crumbs for the Nazis to find. Wheatley created enormous charts detailing what lies to tell on what date, and through what channel. Diplomatic gossip? False reports by double agents? Physical means such as “losing” a rucksack or a dead body? Nothing too direct or it wouldn’t be believable — the Germans had to gradually construct the story themselves.

That is how to write a deception plan. It’s also how to write a novel. The biggest difference was that instead of writing for millions of readers, Wheatley was writing for just one.

The deception plans he wrote to trick Hitler were in many ways echoes of his Gregory Sallust stories, which were all set against the backdrop of real events. For example, in The Black Baroness, Sallust is in Norway during the Nazi invasion. When a small number of British troops arrive to defend Norway, Sallust is elated — but his elation turns to horror as he watches the troops turn and run.

When Wheatley went to work for Churchill, the first deception plan he created was aimed at convincing Hitler the British were invading Norway, with the aim of getting him to tie up troops there. He planned a massive invasion — troops based in Scotland would be given Norwegian translators, maps of Norway, arctic clothing, and training in mountain warfare. (This worked; Hitler sent 50,000 extra troops to Norway.) So this was his second chance to have Britain not invade Norway.

3. Wheatley’s protagonist, Gregory Sallust, is a suave figure, easily envisioned in a smoking jacket, who knows a good vintage champagne and speaks German like a native. But today’s spymasters seem to have dumped the skills of a James Bond (“human intelligence”) in favor of the increasingly sophisticated machines (“signals intelligence”) that now form the crux of their data pool. Is there reason to be nostalgic for old forms of spycraft?

So you have seen Skyfall.

Wheatley lived in both those worlds. Sallust was all human intelligence — the lone wolf outwitting the Germans through his disguises and tricks. As in most pulp fiction of this type, Sallust pretty much single-handedly wins the war. In a later novel, he even infiltrates Hitler’s bunker and convinces the Führer to commit suicide.

But in real life, Wheatley relied heavily on signals intelligence. Since Britain had cracked the German Enigma ciphers, they could listen to the Nazis’ radio communications. Wheatley could thereby tailor his deception plans to what Hitler already knew and believed.

One could argue, however, that the Germans lost the war because they lacked human intelligence. The deceivers’ most important channels to Germany were Nazi agents in Britain who had been doubled. In June 1942, the British came to the astonishing realization that every single German agent in Britain was a double. They would control them for the rest of the war. This meant they could feed the Germans outrageous deceptions with no fear of being contradicted by real agents. Wheatley had started his deception work thinking he had to do everything short of invasion in order to simulate an imminent invasion. But once the deceivers realized there were no real German agents inside Britain, all they had to do was write radio plays.

4. The core of your book is about the outwitting of German intelligence. What vulnerabilities did the Abwehr have, and how were they exploited?

One of the most interesting things I learned researching this book is that for two countries renowned for their discipline and efficiency, Germany and Japan had catastrophically bad intelligence services. Japan particularly. Japanese intelligence was so abysmal that it was actually somewhat immune to deception; you couldn’t fool the Japanese because you couldn’t assume they would draw the desired conclusion from what you fed them, or even notice it at all. “There was a feeling on the part of the general army officers that intelligence was not necessary,” the chief of Japanese Army Intelligence later told U.S. interrogators.

The Abwehr and other German intelligence services were crippled by two factors of which they were unaware: their communications weren’t secret, and the people they thought were their spies in Britain were actually using plot points drafted by Wheatley and his colleagues.

But the Nazis’ most important vulnerability was that their leader was a megalomaniac who made decisions on whim and instinct. There was no coordinated system for filtering intelligence up to Nazi decision-makers, and when it did reach the top, it was often ignored. What crossed Hitler’s desk was determined by which officers he had seen that day. And he would pay attention only to information that supported views he already held — so of course that’s what his subordinates tended to show him.

5. Who was Garbo, and what made him one of the most successful double agents of all time?

Garbo — a Catalan named Jual Pujol — was the only double agent who set out to become one. (The others either defected or chose the job over execution.) Before he was discovered by the British and taken to England, he freelanced for the Allied cause: he volunteered to spy for the Abwehr and convinced them he had gone to England. In reality he was in Lisbon, where he made up reports with the help of some maps, a railway timetable, and a Baedeker travel guide.

Garbo put his nerve and prodigious imagination to work in a different way once he reached England. He transmitted reports to the Germans from his stable of twenty-seven subagents (some of whom themselves had subagents). These were people in key jobs and key cities all around Britain. They were highly productive — and wholly imaginary. It is no mean feat to maintain the trust of your handlers when you have to get everything important wrong, but Garbo managed it. He was surely the only man in history to be decorated with both a British MBE and a Third Reich Iron Cross.

6. You write that “Sallust’s lasting influence can be seen in the career of his true heir, James Bond.” What links Wheatley with Bond’s creator, Ian Fleming, and why has Bond outlived Sallust?

When Wheatley was on the Deception staff, he sometimes worked with a young naval-intelligence officer named Ian Fleming. Fleming was not yet a writer — he would not publish the first Bond novel, Casino Royale, until 1953 — but he was telling friends he wanted to write spy novels. Wheatley kept lists of the dinner guests at his house and we know Fleming was one of them. It is reasonable to guess that Fleming was very influenced by Wheatley, and by Sallust.

Sallust is unknown today while Bond is Bond because of luck. The Bond books would not have survived on their own — the movies keep the character alive. There were no Sallust movies, probably because the war intervened.

The Sallust books are classic pulp fiction — artlessly written but brilliant yarns; Wheatley is very good at getting his characters in and out of mortal peril every few pages. And they are better than the Bond books in many ways. They are full of astute political and military analysis, and they insert Sallust into a world of real figures and important events — he spends nights drinking with Hermann Goering; he tricks Hitler into invading the Soviet Union. And they were written quickly, at times coming out four months after the events they described. It wasn’t the first time an author had put his characters into the middle of real events, but it was perhaps the first time those events threatened to crash through the reader’s living-room ceiling even as he held the book in his lap.