In the spring of 1943 chief of Combined Operations "Dickie" Mountbatten advanced into Winston Churchill's bathroom announcing that he had "a block of a new material" to place in the prime minister's filled bath. The new substance was "pykrete", a compound of ice and sand, which Churchill worried would cool his bathwater. Mountbatten launched it nonetheless and as the miniature iceberg floated miraculously intact in the warm water the two men dreamed of the seaborne airfields and ice ships they would build together, winning the Battle of the Atlantic with ice.
Pykrete was named after its inventor, Geoffrey Pyke, an amateur eccentric whom Mountbatten had recently appointed as his director of programmes. This was the crowning moment in an odd career.
When Pyke killed himself in 1948 he was hailed by his special operations colleague the scientist JD Bernal as "one of the greatest geniuses of his time". Yet because Pyke was restless, never remaining in any field long enough to acquire either fame or riches, he was forgotten in his own time. Now Henry Hemming has told his story in a biography that reads wonderfully like an adventure story and looks set to restore to Pyke the fame he deserves. In the process, he attempts to use his example to teach us all how to think like geniuses, sharing Pyke's view that it is our duty mentally to "throw up a hundred million pollen on the chance that one may do its duty".
Hemming has had the ingenious idea of structuring the book as a series of problems, which seems to be how Pyke himself experienced the process of living. As a Cambridge undergraduate, when the first world war broke out Pyke set himself the challenge of "how to become a war correspondent". In that case, the answer was to go somewhere no other correspondent was prepared to go. At a time when MI6 (then the SIS) was unable to get a single agent into Germany, Pyke managed to reach Berlin as a lone non-German-speaking Englishman. When he was then interned in the notoriously well-guardedcamp at Ruhleben, he set himself the problem of "how to escape". He was so skilled at exiting the camp and making it largely by foot to neutral Holland, that the British government assumed he must have been helped by German authorities.
No aspect of life was too trivial – Pyke applied his full analytic intelligence to everything. When he married and fathered a son called David, in 1921, he asked the psychoanalyst James Glover for advice on the question of "how to give your child a truly enlightened upbringing". Pyke's own childhood had been desperately unhappy, both at home and at Wellington College, where as the only practising Jew he was systematically bullied and "Pyke hunts" were a regular sport. Unfortunately, he could find no educational establishment suitable for his son, so he decided to solve his latest conundrum by founding a school himself, first mastering the stockmarket in order to acquire sufficient funds.
Malting House school was one of the first radically progressive schools in Britain, run by Susan Isaacs with whom Pyke (less successful in problem solving when it came to women) had an intense but ultimately unhappy affair. Inspired by Rousseau and Freud, Pyke and Issacs were determined not to discipline their two-to-seven-year-old charges, who were known as "plants" and encouraged to explore the world as small scientists in the making. The "co-investigator" teachers were there largely to observe the customs of the children. Educationally, the school was a success, though it was known for a time as a "pregenital brothel", but it left Pyke bankrupt, wifeless and reclusive, until he encountered the new challenge of "how to resolve an epidemic of antisemitism" and mustered his resources once again.
Hemmings's problem-solving structure allows the book to be read as a detective story, not least because it is interlaced with "Pyke hunt" chapters in which MI5 (and Hemming himself) investigate the truth behind allegations of Pyke's Communist leanings. It means, though, that Pyke himself remains elusive. Except in one wonderful chapter about his marriage and affair with Isaacs, he is seen from a distance. The reader is given intellectual rather than emotional insights: we think with him but do not always feel with him. When Pyke is told by a Times editor in 1948 that it now seems time for him to solve "the problem of Pyke", he does so by killing himself. Hemming reprints his very moving suicide notes (one to his son ends shakily "Sorry. Sorry. Sorry") and tells us that "we can be sure that during the last years of his life he was in pain, both mental and physical". But we do not go to Pyke's death with him, and his motivation remains shadowy, as do the feelings that guide his astonishing inconsistency.
If Pyke remains enigmatic then that was certainly how he seemed to all those around him, including his child and lovers. We may not end up fully understanding him but we do know more about his circumstances than he knew himself, thanks to the MI5 files that Hemming has uncovered, which provide a satisfactory conclusion to the mystery. Hemmings's great achievement is to turn the story of a nerdish chameleon into a page-turner and to make someone hitherto unknown seem crucial to his century. Pyke intersects with so many of the major causes and figures of his day that his reputation now seems secure.
Most important, we end the book sharing Pyke's belief that the English need to be more open than usual to inventive ideas. "Bad manners to new ideas … are sabotage … they are a Public Offence", Pyke complained on the BBC, shortly before his death. Hemming clearly shares this view and is persuasive in presenting Pyke's case that we need to allow surreality to inform reality, to take laughter seriously and to see the wisdom that can emerge through foolishness.
• Lara Feigel is the author of The Love-charm of Bombs: Restless Lives in the Second World War (Bloomsbury). To order Churchill's Iceman for £15.49 with free UK p&p call Guardian book service on 0330 333 6846 or go to guardianbookshop.co.uk.
