Green’s Dictionary of Slang

bang up v.2

[the banging of the cell door]
(UK prison)

1. [1930s+] to imprison.

2. [1950s+] (also bang out) to lock a prisoner in a cell.

3. [1950s+] to be locked up in a cell.

4. [1980s+] (Aus. prison) to alert a prison officer by banging on one’s cell door.