Green’s Dictionary of Slang

(UK Und.) that member of a team of parcel thieves who actually removes the stolen goods and takes them to a hideout.

1591		Greene Second Part of Conny-Catching in Grosart (1881–3) X 119: The Marker, which is the receiuer of the lifts luggage, giues a winke to the Santar that walkes before the windowe.
1608		Dekker Belman of London G3: He that receiues it is the Marker. He that stands without and carries it away, is the Sentar.