avant-courier

Etymology
From, with alteration of second element after.

Noun

 * 1) A person dispatched before another person or company, to give notice of his or their approach; a scout or herald.
 * 2) * 1808–10,, Memoirs of a Georgian Rake, Folio Society 1995, p. 145:
 * Mr Farrer reached Calcutta some time before them, announcing himself as the avant-courier of His Majesty's new court, in which he was to be the leading advocate.