Green’s Dictionary of Slang

smugger n.

[smug v. (2)]

a thug, specializing in snatch-and-grab thefts; also in fig. use, anyone who steals, e.g. ideas.

[UK] ‘’Arry on the Sincerest Form of Flattery’ in Punch 20 Sept. 144/2: They’ll be arter you, nick over nozzle, the smuggers of notions and nips.