Green’s Dictionary of Slang

nine-bob note n.

[the UK’s pre-decimal currency included a ‘10-bob’, i.e. 10-shilling note, but not a ‘nine-bob’ one]

anyone or anything fake, spurious; esp. in phr. bent as a nine-bob note under bent adj. or ...a nine-bob note under queer as... adj.

Show quotations
[UK]Indep. Rev. 30 June 12: Having the most macho of pouting Greeks singled out as being nine-bob notes, you can never look at an Englishman the same way again.
[UK]Indep. 28 Sept. 15: Dromey weighed in, describing Mr Johnson a ‘tufty toff from Eton’ who was as ‘genuine as a nine-bob note’.
[UK]J. Meades Empty Wigs (t/s) 621: [A] multimillionaire with several estates and a nine-bob-note husband.