Chief Superintendent "Farmer" Watson was an officer in the Lothian & Borders Police. He was originally from Aberdeen, working in the police force there, but was posted down to Edinburgh following the departure of William Anderson at Great London Road. He is described as 'a large man, his girth giving truth to the phrase "barrel-chested". His face was ruddy, hair thin and silver at the temples'. He is married and has two children.

After arriving in Edinburgh and being surprised by the problem of drugs in comparison to his home town, he decided to launch an anti-drugs campaign with the financial backing of James Carew, Finlay Andrews, and Tommy McCall, all prominent figures in Edinburgh. He asked John Rebus to lead the campaign, due his personal experience, and met with the backers and Rebus for lunch in the Eyrie one wednesday. He was invited by Andrews to join his club, but declined as at that time he seldom drank and never gambled. The following friday James Carew commited suicide with an overdose, and Watson trusted Rebus to let the campaign keep face, but that afternoon a prostitute accused Rebus of paying him for sex. Watson gave him the week off until it blew over, but got him an invite to Finlay's club before attending a press conference with Tony McCall. The next day he ended up going to Finlay's Club himself, and met Rebus who had planned an investigation into the dealings of the club unbeknownst to Watson. Rebus dealt with Lanyon and Andrews then explained Hyde's Club to Watson, who called in backup and raided the house, discovering a secret boxing club implicating many members of Edinburgh's high society.

Roughly 2 years later, Watson had heard Rebus blurting out his nickname ("Farmer Watson", due to his agricultural background) and so was assigning him menial jobs and sending him on managerial training courses. Then Watson was contacted by the Metropolitan police, who on the request of George Flight was asking for Inspector Rebus to be posted to London to assist in the apprehension of the "Wolfman" serial killer. Watson sent Rebus down with the parting words "No fuck-ups, John". Rebus proved useful and was essential in the solving of the case.