Green’s Dictionary of Slang

bionc n.

also beyonek, beyong, bianca, bionk
[Ital. bianco, white = silver]

a shilling (five pence).

[UK](con. 1840s–50s) H. Mayhew London Labour and London Poor III 206/2: We could average our duey bionk peroon a darkey, or two shillings each, in the night.
[UK]G.R. Sims ‘Pickpocket Poems’, Dagonet Ditties 91: Of two bioncs I robbed the bard, / For which I got three months with hard.
[UK]Mirror of Life 7 Mar. 3/4: Jack has to vader the homies of the casa where he chucks the tifilo before be can get tres bianca a night.
[NZ]W. Ings ‘Trolling the Beat to Working the Soob’ in Int’l Jrnl Lexicog. 23:1 64: [A] shilling was a beyonek, a half crown, a tosheroon, and a pound a ponte.
[UK]R. Milward Man-Eating Typewriter 147: [T]hese twats might [...] take off with my hard-earned beyongs.