Green’s Dictionary of Slang

martin n.

[? SE martin, a species of bird. It is supposedly lucky for a martin to nest in the eaves of one’s house; poss. in this case it is the robbers who see the appearance of such a martin as lucky for themselves]

the victim of theft, either by a team of confidence tricksters or a highwayman.

[UK]Greene Notable Discovery of Coosnage in Grosart (1881–3) X 37: The Art of Cony-catching. These are the eight lawes of villanie leading the high waie to infamie. In High Lawe. The Theefe is called a High lawier. He that setteth the Watch, a Scrippet. He that standeth to watch, an Oake He that is robd, the Martin When he yeeldeth, stouping.
[UK]Dekker Belman of London G4: Hee that is robd, is the Martin.
[UK]Rowlands Martin Mark-all 51: I haue heard and partly know a high-way lawyer rob a man in the morning, and hath dined with the martin or honest man so robbed the same day at an Inne being not descried.

In compounds