If you were looking for a model protagonist for a ripping yarn, you could do a lot worse than John Burdon Sanderson Haldane, known to his colleagues as JBS, his intimates as Jack and his father as Boy. He was born in 1892, when the British Empire was in its pomp. The Haldanes could trace their ancestry back to the 12th century, when the ‘Half-Danes’ held a strategic pass north of Edinburgh. Although they lived in Oxford, the Haldanes summered at an ancestral pile in Scotland, where Jack and his adoring sister, Naomi (best known as the novelist Naomi Mitchison), ran wild in the woods and fields.

Jack’s uncle was the Liberal politician R B Haldane. His father, John Scott Haldane, was a pioneering physiologist who had a laboratory at home and was often called on by the government to offer advice on air quality. Jack was encouraged to participate in experiments, some of them deliciously dangerous. In those days, scientists were wont to experiment on themselves. In the case of Haldane senior, that also meant his son. This could involve being sent to the bottom of a freezing loch to test breathing equipment. ‘To Jack, this was all a screaming adventure,’ Samanth Subramanian writes. Although Jack and Naomi would do experiments together, including breeding mice and guinea pigs to test ideas of inheritance, their father included only Jack in his more wizard wheezes.

Jack went to the Dragon School, then Eton and Oxford, where, despite his healthy interest in science, he studied mathematics and, just because it was there, classics. Rebellious, awkward, ebullient and fearsomely clever, he read everything and forgot nothing: well into later life he could reel off, from memory, classical