Most memoirs of the Third Reich appeared well after the war, full of hindsight, aiming to distance the author from the regime (“I was only obeying orders”). This one, however, appeared in 1940, at Hitler’s zenith, written by an exiled colleague with whom he had split ten years earlier.

Otto Strasser had been an early supporter of the Nazi party, inspired by the word ‘Socialist’ in its official title. But Hitler was realising that he could not achieve power by alienating corporate business such as Krupp and Thyssen, and had started to peddle his vision of a pure, conservative (Wagnerian) Germany, purged of greedy, sinister Jews. The gap between the two wings of the party could not be bridged, and Strasser was expelled and exiled, long before Hitler became chancellor.

The narrative ends in 1940, during the phoney war. But he is able to slip in a last-minute update (June 1st), usually a bad stylistic, but of great interest in the present case. For he predicts that England is about to experience its worst hammering, but he doesn’t think it will lead to a successful invasion, and he declares that most Germans do not support Hitler - effectively betting that the Allies will win.

We don’t know for certain whether he actually meant any of this, for he was strongly motivated to smear the Führer, not only for wrecking his career, but also for murdering his brother in the Night of the Long Knives. Yet it raises another controversial issue. For Strasser is the only source for the much-repeated sensationalist rumours about Hitler’s sexual predilections, which supposedly drove his niece Angela (“Geli”) to suicide while they were living together in Munich.

To me, that story had always rattled a bit. For one thing, many believed that their relationship was platonic. Also the rumours related to a fairly common practice (urolangia) that could have been no more than mildly annoying to an unwilling partner, hardly suicide country. Whereas what she certainly found unbearably stressful was the house-arrest in the final weeks, after he’d discovered that she had a Jewish boyfriend in Vienna. From then on, she could only leave the house on Hitler’s arm, and when he was away on business, sometimes for days on end, she would be confined indoors. For a high-spirited young woman who loved parties and dances, this would have felt profoundly unnatural, and the prospect could well have driven her to the brink.

Even then, I doubt that it was suicide. Hitler had stormed out of the house in a violent rage, and I could well imagine a Thomas a’ Becket moment: “Who will rid me of this turbulent niece?”, where one of his gang sees a chance to score points. (Certainly Hitler’s lifelong guilt about her death seemed to echo King Henry’s obsessive penance.) Yet Strasser thinks - or claims he thinks - that it was Hitler himself who did the deed, presumably entering through a window, as the housekeeper had been alerted by the sound of the shot.

Finally, there’s new light on Hitler’s early political career. I had assumed that it was just a lottery when Corporal Hitler was told to spy on the German Workers Party (DAP), regarded as so insignificant that it could safely be left to a lowly NCO. But apparently a certain Captain Ernst Rőhm, who already knew Corporal Hitler well, had selected him for the job, little dreaming that he would die directly at Hitler’s hands on the Night of the Long Knives.