Green’s Dictionary of Slang

rattle and clank n.

[rhy. sl.]

1. orig. naval, a prison [= tank n.2 (1)].

J. Wynnum Tar Dust 76: ‘An’ look lively about it or I’ll slap you in the rattle for feigning sickness’.
[UK](con. WW2) T. Jones Heart of Oak [ebook] I’d had a knee trembler with a bird outside the Heffelent and got a nap hand ... and I went adrift ‘cos I didn’t want to be in the rattle for the next bleeding ten years.

2. a bank.

[UK]Dodson & Saczek Dict. of Cockney Rhy. Sl.
[UK]R. Puxley Fresh Rabbit.
[UK]B. Kirkpatrick Wicked Cockney Rhy. Sl.