Green’s Dictionary of Slang

(UK Und.) a poor quality soup served up to convicts, esp. those imprisoned on the hulks.

1825		Knapp & Baldwin Newgate Calendar III 489/1: The Water in which the beef was boiled is thickened with barley, and forms a mess called smiggins.
1830		W.T. Moncrieff Heart of London II i: I’ll give you a dish of smiggins.
1839		W.A. Miles Poverty, Mendicity and Crime; Report 112: He would rather live upon skilly and smiggen for seven years than go abroad.
1859, 1860		Hotten Dict. of Modern Sl. etc.
1864, 1867, 1870		Hotten Sl. Dict.
1869		Australasian (Melbourne) 17 July 8/5: The broth given on board the hulks is called skilligolee, skilly, and smiggins.
1897		‘Price Warung’ Tales of the Old Regime 41: The buckets of ‘smiggins’ were waiting to satiate their appetites.