Some people might say that white supremacists have been ‘emboldened’ in Trump’s America because they were there all along; others might say they were there all along. What do you think after writing this book?

“I have a visual image when I think about this: There’s always been a stream of both racial and religious intolerance, and that stream goes as far back in the United States as I am aware. But there are two things happening now: One is that racist groups are growing and attracting new people. The other is that they are publicly, proudly proclaiming their views, and that is really dangerous. One thing I really worry about is how for a short period in the 1920s, the second Klan made it respectable to mouth these really foul racial slurs; it was totally legitimate and even respectable. Then WWII, and the struggle against the Nazis, sort of stigmatised racism, and certainly anti-semitism, because that’s what the Nazis built their regime around. When racism goes underground, it’s because people have the sense that others are disapproving. But it’s so overt now, and that concerns me.”