Green’s Dictionary of Slang

a professional criminal.

1960		Observer 24 Jan. 7/2: Suppose [...] a bogy did get it up for a villain now and again by making sure that some gear was found in his flat?
1972		P. Fordham Inside the Und. 21: ‘Villain’ [...] is, in fact, the normal name for a professional criminal as used by the criminals themselves and the police.
1984		Smiley Culture ‘Cockney Translation’ 🎵 Me say strictly con-man also the villain.
1995		D. Lodge Therapy (1996) 2841: There’s all sorts of villains round ’ere. You might be burgled while you’re away.
2004		(con. 1980) N. ‘Razor’ Smith A Few Kind Words and a Loaded Gun 247: Jimmy would be propping up the bar in a well-known ‘villains’ pub’ every Friday.