knight of the post

plural knights of the post

1. idiomaticobsoleteA known perjurer; a professional false witness.

   A knight of the post […] quoth he, for so I am termed; a fellow that will swear you anything for twelve pence.

   1592, Thomas Nashe, Pierce Penniless

   2 more examples

   […] But with more lucky hit than those That use to make the stars depose, Like knights o' th' post, and falsely charge Upon themselves what others forge; As if they were consenting to All mischief in the world men do […]

   1662 (indicated as 1663), [Samuel Butler], “[The First Part of Hudibras]. Canto I.”, in Hudibras. The First and Second Parts. […], London: […] John Martyn and Henry Herringman, […], published 1678, →OCLC; republished in A[lfred] R[ayney] Waller, editor, Hudibras: Written in the Time of the Late Wars, Cambridge, Cambridgeshire: University Press, 1905, →OCLC

   [T]he fugitive had been cajoled by a certain knight of the post, who undertook to manage the thousand pounds in such a manner, as would, in a very little time, make him perfectly independent […].

   1751, [Tobias] Smollett, The Adventures of Peregrine Pickle […], volume (please specify |volume=I to IV), London: Harrison and Co., […], →OCLC

   Synonyms: hockettor