Obviously I did want to write about these things. I’d be being disingenuous if I said I didn’t want to. But I never approach a piece of writing with an allegory or a political dimension that I want to cram into it – it’d be approaching arse-end on! I start with the situation and the characters, and really I thought in terms of what those aliens would do would probably look quite like how we tend to fight wars now. They’re a kind of minority of a minority. There are only 20 million Zygons in the world, like Clara says, against 7 billion people. And there is a section amongst that who are interested in making wars. So they would probably have to fight a war in the ways that we tend to see nowadays.

But then you start thinking, what are the best psychological weapons of shapeshifters? They can turn into your family, and do things like that.

I’ve been following the news, and I was keen to write something about it. But I didn’t approach it from that way. It just became a good kind of environment in which to borrow things from that, and tell a sci-fi story. Because I also don’t believe in telling people what to think.

I think certainly in this and Kill The Moon, I tried not to read too many things about it. But people find ways of finding you, and I’ve been called a raving lefty Marxist, a disgusting Conservative, and everything in between! For me that says I’m doing my job well: I’m presenting something for discussion, I’m not reaching a conclusion. I don’t believe that drama, or art, is there to provide answers. It’s not to tell people what to think, it’s to encourage people to think, and come up with answers themselves.