Green’s Dictionary of Slang

a shilling (5p).

1839		H. Brandon Dict. of the Flash or Cant Lang. 161/2: Breaky leg – a shilling.
1857		J. Archbold Magistrate’s Assistant (3rd edn) 446: A shilling. Breake-leg.
1864, 1867, 1870		Hotten Sl. Dict.
1874		Derbyshire Courier 12 Dec. 7/1: Local Flash language [...] A breaky-leg, a shilling.
1881		Morn. Bulletin (Rockhampton, Qld) 18 July 2/6: For a shilling there are many names but nearly all slang. [...] ‘Breaky-leg,’ ‘brongs,’ ‘bobs,’ ‘bordes,’ ‘drawers,’ ‘gens’, ‘hogs,’ levys,’ ‘pegs,’ ‘stags,’ ‘Shigs,’ ‘twelvers’ and ‘teviss’s’ .
1889		Clarkson & Richardson Police! 320: A shilling ... A bob, breaky, deaner, midgic.
1905		Exeter & Plymouth Gaz. 4 Feb. 5/6: A shilling was known as a ‘breaky-leg’.
1925		(ref. to 1850s) Western Mail (Perth) 28 May 21/1: [from Daily Mail, London]At the time of the Crimean War bob was only one of a number of terms [for a shilling] such as twelver and breaky-leg, gen and teviss, stag, deaner, hog and levy.