of a possible attack scenario and the extent of the damage were derived from Doomsday, Britain after Nuclear Attack (1983), while the ineffective post-war plans of the UK government came from Duncan Campbell's 1982 exposé War Plan UK. In portraying the psychological damage suffered by survivors, Jackson took inspiration from the behaviour of the Hibakusha and Magnus Clarke's 1982 book Nuclear Destruction of Britain. Sheffield was chosen as the main location partly because of its "nuclear-free zone" policy that made the council sympathetic to the local filming and partly because it seemed likely that the USSR would strike an industrial city in the centre of the country. Jackson hired Barry Hines to write the script because of his political awareness. The relationship between the two was strained on several occasions, as Hines spent much of his time on set, and apparently disliked Jackson on account of his middle class upbringing. They also disagreed about Paul Vaughan's narration, which Hines felt was detrimental to the drama. As part of their research, the two spent a week at the Home Office training centre for "official survivors" in Easingwold which, according to Hines, showed just "how disorganised [post-war reconstruction] would be." Auditions were advertised in The Star, and took place in the ballroom of Sheffield City Hall, where 1,100 candidates turned up. Extras were chosen on the basis of height and age, and were all told to look "miserable" and to wear ragged clothes; the majority were CND supporters. The makeup for extras playing third-degree-burn victims consisted of Rice Krispies and tomato ketchup. The scenes taking place six weeks after the attack were shot at Curbar Edge in the Peak District National Park; because weather conditions were considered too fine to pass off as a nuclear winter, stage snow had to be spread around the rocks and heather, and cameramen installed light filters on their equipment to block out the sunlight. Although Jackson initially considered casting actors from Granada Television's Coronation Street, he later decided to take a neorealist approach, and opted to cast relatively unknown actors in order to heighten the film's impact through the use of characters the audience could relate to. In order for the horror of Threads to work, Jackson made an effort to leave some things unseen: "to let images and emotion happen in people's minds, or rather in the extensions of their imaginations." He later recalled that