Nuclear wars had led to the birth of a sizeable population of mutants through showers of Strontium-90 in nuclear fallout. After the Great War of 2150 ("Nobody ever knew who fired the first missile - but suddenly the whole world went crazy!"), wiping out 70% of Britain's population, the number of mutants increased and was met with loathing by the "norms" and institutionalised racism: laws were passed forbidding mutants from owning businesses and segregating them into ghettos such as Milton Keynes, and only a vicious guerilla war prevented total extermination of all mutants and ensured some basic freedoms.