sarbot, n. — Green’s Dictionary of Slang

sarbot n.

also sarb, sarbut

[Partridge DU suggests ‘The word is suspect’ but cite 1947 suggests some validity]

(UK und.) an informer.

1928		F.C. Taylor ‘Language of Lags’ in Word Lore Oct. n.p.: sarbot: an informer.
1935		Thieves Slang ms list from District Police Training Centre, Ryton-on-Dunsmore, Warwicks 7: Old sarb: Informant. [ibid.] 9: Sarbut: Police informant.