By 1983, Kennedy Martin had written the first draft of what became "Edge of Darkness" – at this stage it was called "Magnox" (a reference to the Magnox type of nuclear reactor) and was about trade union problems in the nuclear industry. The script was given to BBC Head of Drama Series & Serials, Jonathan Powell, who encouraged Kennedy Martin to continue its development. The script went through many changes and revisions. A particular influence was the speech made by President Ronald Reagan on 23 March 1983 announcing the Strategic Defense Initiative (SDI) which proposed protecting the United States from attack by nuclear missiles. One of the supporters of SDI was Lyndon LaRouche, on whom Kennedy Martin based the character of Jerry Grogan, owner of the Fusion Corporation of Kansas. Kennedy Martin was also influenced by the secrecy surrounding the UK's policy on nuclear power in light of the inquiry into the construction of the Sizewell B nuclear power station and the concerns about the safety record of the Sellafield nuclear reprocessing plant; this led him to conceive International Irradiated Fuels and its chief executive Robert Bennett.