In Mrs Bradshaw's Handbook, Mrs Georgina Bradshaw describes the newly-formed Railway Police, who defend the interests of the company and the City on all trains, tracks and stations. Thus fulfilling Sam Vimes' desire to bring some sort of law to places like Zemphis, and, no doubt coincidentally, extending the writ of Lord Vetinari and City law over hundreds more square miles and lots of valuable real estate. As well as to all those small towns and cities nominally outside Ankh-Morpork's current borders, with either rudimentary or no jurispudence of their own, but which have expressed at least tacit willingness to accept Ankh-Morpork law as colourfully and effectively embodied in Sam Vimes. The Railway Police are a semi-detached and necessarily highly mobile adjunct to the Ankh-Morpork City Watch, who patrol up and down the hundreds of miles of track and add a highly visible level of security in railway stations, stock yards and other Railway real estate. Their uniforms are distinguished by badges bearing the Ankh-Morpork civic arms and the railway company cipher.
Details of Railway Watch members, senior ranks, et c, are not known yet. but circumstantial evidence in Raising Steam suggests Sergeant Fred Colon and Corporal Nobby Nobbs would not be averse to patrolling a beat where they can sit down comfortably indoors in the dry most of the time, letting the train take the strain, without even the minimal physical exertion involved in Proceeding.