Sam Youd was born in Lancashire in April 1922, during an unseasonable snowstorm.As a boy, he was devoted to the newly emergent genre of science-fiction: 'In the early thirties,' he later wrote, 'we knew just enough about the solar system for its possibilities to be a magnet to the imagination.'Over the following decades, his imagination flowed from science-fiction into general novels, cricket novels, medical novels, gothic romances, detective thrillers, light comedies ... In all he published fifty-six novels and a myriad of short stories, under his own name as well as eight different pen-names.He is perhaps best known as John Christopher, author of the seminal work of speculative fiction, The Death of Grass (today available as a Penguin Classic), and a stream of novels in the genre he pioneered, young adult dystopian fiction, beginning with The Tripods Trilogy.'I read somewhere,' Sam once said, 'that I have been cited as the greatest serial killer in fictional history, having destroyed civilisation in so many different ways - through famine, freezing, earthquakes, feral youth combined with religious fanaticism, and progeria.'In an interview towards the end of his life, conversation turned to a recent spate of novels set on Mars and a possible setting for a John Christopher story: strand a group of people in a remote Martian enclave and see what happens.The Mars aspect, he felt, was irrelevant. 'What happens between the people,' he said, 'that's the thing I'm interested in.'