'In 1834, aboard HMS Beagle, Charles Darwin wrote to his sister: 'My servant [Syms Covington] is an odd sort of person; I do not very much like him; but he is, perhaps from his very oddity, very well adapted to all my purposes.' When I first read this letter (quoted in the joint biography, Darwin, by Adrian Desmond and James Moore) I realised that if I were ever to write a novel about Darwin, then here was the novel in embryo.'
A convention of the novel is the character from the margins, someone present at a key event, plausible as an 'eyewitness' but not necessarily a main actor dramatically. Covington surpassed the convention by playing the role in real life and supplying the dramatic necessity. Later I read in Janet Brown's Voyaging her opinion that Covington was the unconscious shadow behind Darwin's every triumph. This was more my Covington than the person I'd sighted in the scant historical record. After his employment with Darwin ended, Covington came to live on the margins - in Australia'