I wanted him to use all his experience and intuition and empathy with people who'd grown up around him in Sheffield and put that into the movie, and … - Mick Jackson

Barry came up with the idea of the two families – one working class, the other lower-middle – and what their lives were like. Sheffield seemed a good place to set it, and Barry knew it well. It was bang in the middle of the country, and a good way from London. Strategically, it also made sense: there were industrial and military targets nearby.
Both of us were interested in the idea that none of these characters would ever have a god’s-eye-view of events, and never find out what was happening outside their immediate experience, certainly not outside Sheffield. That seemed to be the way most people would have to deal with a nuclear apocalypse, with most forms of communication vaporised.

The real effect of a nuclear weapon is not what it does to things, to buildings, to cities: it's what it does to society, what it does to people, what it does psychologically. I was very struck by the work that an American writer called Robert Jay Lifton had done on the psychological effects of the bombings of Nagasaki and Hiroshima on the survivors and I talked to him a lot. It seemed to me that the story that needed to be told was the story of what this does to society as well as what it does to physical things, and you could only really tell that with a drama, with people that you identified with.

I remember a scientist who worked on the Manhattan Project said to me "you know, when I hear people talking about winnable nuclear wars, I just wish I could take them to the Mojave desert, the Nevada desert, wherever, strip them down to their underwear, and let them watch an actual nuclear explosion from miles away, feel the blistering heat pulse on their skin, and feel the blast wave sweep over them and shake their heart and their lungs around inside their rib cage. Then they would have a sense of what it was they were talking about and they wouldn't talk about a winnable nuclear war."