Green’s Dictionary of Slang

1. the Central Criminal Court, London; generally known as the Old Bailey.

1984		Partridge DSUE (8th edn) 41/2: mid-C.19–20.
2000		J.J. Connolly Layer Cake 225: Don’t wanna be asking Postman Pat so he can have a day out up the Bailey.

2. (Aus.) prison in general.

1885

Bulletin (Sydney) 3 Jan. 6/2: Then, leaving the establishment his splendid and elastic hiccup blew the town clerk’s hat off [...], after which he quietly subsided into the lock-up; and there, during the night, he continued, in his cool but cheerless cell, to extol the praises of bailey.