E. Cobham Brewer 1810–1897. Dictionary of Phrase and Fable. 1898.
Knights o’ the Post.
Persons who haunted the purlieus of the courts, ready to be hired for a bribe to swear anything; so called from their being always found waiting at the posts which the sheriffs set up outside their doors for posting proclamations on.
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“There are knights of the post and booby cheats enough to swear the truth of the broadest contradictions.”—South.
“‘A knight of the post,’ quoth he, ‘for so I am termed; a fellow that will sweare you anything for twelve pence.’”—Nash: Pierce Penilesse (1592.)
