Patrician Havelock Vetinari has no standing army and such government agencies as exist in Ankh-Morpork (the City Watch, the Mint, the Post Office) operate at an arm's length. The arm can become very short and strong when necessary, but his motto is Si non confectus, non reficiat. The Ankh-Morpork civil service consists mainly of black-robed, tight-lipped men 1 in every specialty from simple clerks through accountants to assassins. These form a very efficient information-gathering and processing body (body-processing, occasionally, for the assassins) which keeps Vetinari on top of and usually ahead of local and world events.
The clerks' routine tasks are collecting information, preparing reports and maintaining the extensive palace files. Now and then some emergency or suspected crime will invoke a Concludium, a fact-finding exercise akin to a Royal Commission or Senate Investigation only much faster. All the clerks in specialties related to the matter at hand convene and sift evidence with computer-like efficiency until the solution is found, likely within a day.
The Chief Clerk and Vetinari's right-hand man currently is Rufus Drumknott, a quiet, studious type who has occasional difficulty with the dry Vetinari wit. This is preferable to his more imaginative but totally mad predecessor Lupine Wonse. Inigo Skimmer was a member of the "black-ops" section: a skilled assassin, but no match for a werewolf.
1 Some of Lord Vetinari's best friends are women and he has great respect for the talents of Lady Margolotta, Adora Belle Dearheart, Rosemary Palm and others. Clerks, however, are men. Dark Clerks, the other sort, may be of both sexes and indeed of all species. Vetinari is known to retain a golem as a Parole Officer, and at least one gargoyle works as a surveillance agent whose job is simply to listen, inobtrusively, and to report back afterwards.