That’s an easy question. It was, of course, George Balanchine. He came from Russia via Europe and settled in America in 1933. He started a little company which was not very successful, so he had to start over and over again. Ultimately, he founded the New York City Ballet. I happened to be born at the right time, came to the right place, and had the fortune to audition for him, and work with him, because he is the genius of the century of ballet. I learned how to dance with him.

Professor Randall was a great advisor and a great mentor. He taught me, I think, in the best possible way. He was not a brilliant lecturer. His courses were fairly pedestrian. I didn’t think his seminars were particularly interesting. But working with him on a one-to-one basis as his assistant, I think that’s the way one has to learn to be a historian. That is, he was writing, and if he needed some particular reference, I had to go find it and get it. If he was writing, he wanted everything checked meticulously over and over again. So I had to take the manuscript over to the library and check it all out. So that by working closely with him, I got to see, first of all, a lot of the library and its extensive holdings, but I got, even more important, to understand what a scholar is about. It is about care. It is about “pains-taking.” It is about judgment as well as it’s about very skillful writing. He was an excellent writer as well. So in that sense, Professor Randall and Mrs. Randall shaped my future career.

So living with my dad for sure influenced me.

I don’t know if that is true. There have been 110 or more years of cinema, and it’s impossible for any one of us to make a film that can’t be compared to something that has come before. To me Blue Velvet is Blue Velvet and Rear Window is Rear Window. You could say that Sunset Boulevard or Rear Window has conjured an idea for me, but even though I love them or am inspired by them, life is a 24/7 movie. Ideas come out of that all the time. It’s hard to say it’s cinema that conjures ideas. It’s altogether.

Having a family can be a rude awakening for some people but it wasn't like that for me. I've absolutely loved it and I still do. I've got two daughters, Polly and Camilla, in their late 20s now. You get these people who say, "Wait for the terrible twos," and, yes, they've had the odd flounce, but they've got increasingly joyful to be around. My wife Alice and I are very close to them and value their company hugely.

Foolhardiness. I wrote two chapters and a synopsis, sent it off to a publisher, and it sold. That's what emboldened me to continue.

Specialisation leads to extinction. We are learning more and more but about less and less, and one day we will know everything about nothing. There is nothing wrong with being a populist. It does not have to mean dumbing down, as people think.

That I have lost both my parents.

I hope that it exists. I'm not sure I can fit everything in before then.

I try to be a Sherlock Holmes of botany. It's not enough to enjoy plants – I want to know why they are wilting, to work things out.