Doctor Stayling was an engineer who lived around the late 400s TE. He was the head of the Order of Engineers, later the Guild of Engineers. He was described as having a 'North Country' accent, which indicates he could be from Scotland or Scandinavia, perhaps even further in the Ice Wastes.
Stayling was described as being quite hairy, despite shaving his head as per tradition of the Order of Engineers. By the time of Fever Crumb, he had grey hair indicating that he was in his fifties or sixties.
Stayling was somewhere from the North, presumably moving down to London not long before the Scriven's two-hundred year rule of London was starting to slip. Whether he was a travelling technomancer (a person of technological expertise among the Nomad Empires; a kind of 'tech-shaman') or he simply went to London to join their Order of Engineers is not known.
He initially helped Nicola Quercus convert London into the first traction city, but then turned to the London Underground, a secret group of Londoners who wanted to stop London being converted into a traction city; Dr Stayling was dismissed as head engineer and the position was given to Wavey Godshawk by Nicola Quercus.
Eventually Stayling, along with his small band of comrades, were executed by Quercus after Charley Shallow informed on them.