Green’s Dictionary of Slang

villains, criminals.

1900		Sporting Times 28 Apr. 1/2: According to a certain breezy young racing man, more noted for the up-to-dateness of his rhyming slang than for his sobriety, he lost his Epsom winnings through getting ‘picked up by the San Toy’s’.
1932		‘P.P.’ Rhy. Sl.
1960		J. Franklyn Dict. of Rhy. Sl.
1972		Dodson & Saczek Dict. of Cockney Rhy. Sl.