The news that the science fiction author John Christopher died this week at the age of 90 has had me thinking about the influence his books had on me. The Tripods and the Sword of the Spirits trilogies had a huge effect on me when I read them as a teenager. They helped to shape my tastes in literature for life, and I still have vivid memories of them.

Coincidentally, I picked up my old copy of The White Mountains, the first book in The Tripods trilogy, the other day and started to re-read it for the first time in years, unaware that John Christopher had died. The Tripods are huge alien machines that rule the earth at some time in the not-too-distant future, keeping the human race subjugated with mind-control caps that are fitted to teenagers as they come of age. A group of boys escape their cappings and begin a journey that will lead them to discover who controls the Tripods, and what they can do to overthrow them. Many people my age will remember The Tripods from the excellent 1980s BBC TV series that was made (although never completed).

John Christopher had the knack of creating complex, believable post-apocalyptic worlds dominated by authoritarian power structures. That was fascinating to me as a teenage reader, just forming my own views on the power structures of family, society and state in our own world.

To celebrate his writing, I’ve started reading his adult science fiction novel, The Death of Grass, which has just been published in the Penguin Modern Classics series.