LAURENCE REES: Another thing they were doing was looking to see whether they could isolate out whether Jewish people had a particular type of blood - different from everyone else. How can we try to understand this kind of craziness?

RICHARD EVANS: Well, we’re looking at all this with hindsight of course, there are a lot of intelligent people now who don’t believe that global warming is happening, or that if it is happening its not by human agency. Hindsight will put them in a different light no doubt, but for the moment there’s an argument going on. In the 1930s belief in heritage, the inherited nature of very many human qualities, was extremely widespread not just among Nazis but much more generally right across a political spectre. Many British people on the left - HG Wells, George Bernard-Shaw and so on, also believed in eugenics and in the science of heredity.

Racism is extremely widespread in the 1920s and 1930s and not just in Nazi Germany, though the Nazis took it to the logical extremes. It’s very easy now to look back at the absurdities, for example, the Nazis never decided whether Jewish blood was so virulent and terrible that merely having one Jewish grandparent would, as it were, contaminate you or whether German blood was so healthy and so powerful that it would kind of limit the influence of Jewish blood. The Nazis thought that Jews were in some way physically marked and that because Jewishness was inherited Jews looked different, but in fact it’s not true at all, so the Nazis had to make them wear a yellow star so people could actually tell if someone was a Jew which was an admittance that you couldn’t tell who was a Jew. They tried to define a Jew by the number of Jewish grandparents you had but the only way they could define that was by their religion, the religion of the grandparents, which had got nothing to do with racial qualities. So there are many, many absurdities which there are in all racist doctrines but nevertheless intelligent people believed that with time you could isolate racial characteristics, and that’s why they had all these institutes for racial research and racial hygiene to try and pin all this down.

LAURENCE REES: And as you say this was central to what Nazism was. This is not at the periphery, this is at the core.

RICHARD EVANS: Racism was absolutely central to Nazi beliefs, yes.

LAURENCE REES: Even without using hindsight, is it not quite extraordinary that so many of the people around the conference table at Wannsee had PhDs, many in academic law. And yet they are talking clearly about mass killing on a hitherto undreamt of scale?

RICHARD EVANS: Yeah, that’s right.

LAURENCE REES: Because their careers were dependent on it? Or they see this as the correct 'solution'? Or because they hadn't thought of the original idea and they were charged not with originating all this but simply implementing it? How should we see Wannsee?

RICHARD EVANS: Well yes, they were there at the Wanssee Conference at the beginning of 1942 to discuss ways of implementing the extermination. That it would happen, was happening, was already clear to everybody there, and I think it was a meeting in order to sort of smooth the bureaucratic path to the extermination of Jews from across Europe. That was why the foreign office representative was there for example - I think you have to think of it in ways again that relate to other countries, there’s no real compunction in many civil services about enslaving or killing the racially inferior, let's say in Africa or Australia, but not on this scale or with this deliberateness. But still there’s a belief that life is cheaper for people of an inferior racial stock and that I think informed educated people in many different countries, not just in Germany.

What’s different is, of course, the ideological drive of the Nazis and their belief that the Jews are not just racially inferior but also an enormous global threat. It’s not like the Africans in the British Empire or even Slavs for the Nazis, although they want to kill millions of them. They’re not just inferior they’re also this huge global enemy that has to be eliminated if Germany’s going to survive.

LAURENCE REES: So simultaneously inferior and superior?

RICHARD EVANS: That’s right yes. They’re not just sub human they’re more than that in a way.