Green’s Dictionary of Slang

(bingo) the number ten.

1926		Portsmouth Eve. News 23 Nov. 4/4: A man with [...] only £1 or £2 is a ‘case phunt’ or a ‘deuce phunt’. If he has £5 he is a ‘flim’. £10 an ‘Uncle Ben’, and more than that a ‘John Peel’ or a ‘Sarker’.
1943		M. Harrison Reported Safe Arrival 85: ‘Ten’ is [...] rarely ‘Cock and Hen’ or ‘Uncle Ben.’.
1972		Dodson & Saczek Dict. of Cockney Rhy. Sl.
1992		R. Puxley Cockney Rabbit.