Green’s Dictionary of Slang

pothouse n.

[potty adj.1 (4)]

a madman, one who goes to excessive lengths, esp. criminal.

[UK]J.J. Connolly Layer Cake 11: Out of the shadows appeared Mister Mortimer, the legendary pothouse of the parish, who had heard about my supply problems on the jungle telegraph.
[UK]J.J. Connolly Viva La Madness 20: A belligerent pothouse who would bite your nose off.