AR: So when you published Albert Speer's Inside the Third Reich you knew that this was going to be a massive bestseller, but were you criticised for doing it? 

GW: I was criticised by a lot of people who said I did too many books on Germany. But, with the exception of Speer, who had me fooled, what I did was add introductions by English authors, and then the German authors didn't get a penny of royalties from it. There would be books on the Auschwitz commandant Rudolf Höss with an introduction by Alan Bullock, or Hugh Trevor-Roper editing and talking about Hitler's letters. 

AR: But were you criticised by Jews?

GW: By Jews. But other people saw the point — that it was very important to have a horrible book like the one on Commandant Höss with an introduction psychoanalysing his mentality. Speer was the only one I believed in because of his openness, his frankness and his remorse, but now I believe he was the worst, because he was so clever.

AR: What persuaded you? Was it the biography by Gitta Sereny? 

GW: No, it was much more specialised technical literature from Germany by Berlin professors who proved that Speer knew about the Holocaust and that he inspected the machines. But this was much later.

At the time, there was a moment when he had me saying he was a scoundrel one minute, and then, "By God, you're an honest and brave man" the next. How? This is what happened: before we published his book, which we did, we had a very close friendship and business relationship with Michael and Pamela Berry, and when the Sunday Telegraph serial was created, Michael Berry gave me a retainer to help him look for serial material, as the Sunday Times had a virtual monopoly on serialisations. 

When Pamela came in with me bidding for the Speer memoirs and they bought them and I did the book, it came to the point where we wanted to meet Speer for the first time, and he'd only recently been released. So we decided to have a dinner party for Speer, Pamela, Gordon Brook-Shepherd (who was then the diplomatic correspondent handling the serial), myself and one or two Germans. 

Speer's English was correct-to-perfect, but it was very tiring — they asked him lots of questions, "What was Hitler really like?" and so on, and by midnight he was exhausted. And when the party broke up into private conversations I said, "Professor Speer, just tell me one or two things. What made Himmler so important? Because from all we know, he was a mediocre man." "No," he said, "this man had a genius for finding the best people." And as soon as he'd said it, he knew what he was saying, and added, "But [he was] a man of satanic disposition." That pause of four seconds made me think, "My God." 

And then he made it good again. What did he do? He said, "I must tell you now: Hitler had a magnetic personality. I risked my life, having defied his orders, having countermanded the famous Operation Nero in which I would have destroyed all German industry. I went to say goodbye in the bunker and he could have had me killed. He wouldn't shake my hand at the end. I left crying." I assumed that he must be honest to tell that story. Who would tell such a story? But that was all calculated, he was a brilliant maître en scène.

AR: When you came away from meetings like that, did you take notes? Did you keep diaries?