Green’s Dictionary of Slang

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

2000		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.
2011		J.J. Connolly Viva La Madness 20: A belligerent pothouse who would bite your nose off.