Green’s Dictionary of Slang

(UK Und.) a watch; thus jerry and slang, a watch and chain; jerry-getting, jerry-nicking, jerry-stealing, watch stealing.

1873		Sl. Dict. 202: Jerry a watch. ‘jerry nicking’ or ‘jerry sneaking’ is watch-stealing, which is a distinct form of street robbery, and requires both courage and dexterity; for it is done, as the thieves say, ‘right afore a bloke’s face.’.
1885		M. Davitt Leaves from a Prison Diary I 113: If the watch is fastened to its chain by a bar, it is deftly broken off (‘breaking off a jerry’) by the thief’s fingers.
1886		W. Newton Secrets of Tramp Life Revealed 9: Jerry Stealing ...Stealing a Watch.
1895		Crowe Aus. Sl. Dict. 11: Breaking off a Jerry, breaking off a watch-chain.
1899		Sketch (London) 22 Feb. 18: ‘I run up against a toff with a jerry and slang (watch and chain) strung across ’is weskit’.
1904		Sun (NY) 10 July 29/4: Here is a genuine letter written in thieves’ slang, recently found by the English police [...] They made owt finups, a couter, a red jack, and jerry, and a red spark-prop.
1931		‘English Und. Sl.’ in Variety 8 Apr. n.p.: Thimble or gerry — Watch.