Green’s Dictionary of Slang

a lavatory.

1985		(con. 1920s) A. Blair Tea at Miss Cranston’s (1991) 3: All the families shared the landin’ cludgey.
1996		A. Close Official and Doubtful 189: Flushing your facepowder down the cludgie every time the polis turn up at the door.
1997		Roger’s Profanisaurus in Viz 87 Dec. n.p.: cludgie n. Shithouse (qv); lavatory; thunderbox.
2009		T. Black Gutted 17: I [...] nashed through to the gents’ cludgie.