Green’s Dictionary of Slang

breakyleg n.2

[the concept is an old one. Hotten (1860) notes that ‘in the ancient Egyptian language the determinative character in the hieroglyphic verb “to be drunk” has the significant form of the leg of a man being amputated’; also dial. phr. ‘been to Bungay fair and broken both his legs’, he is drunk]

strong drink, esp. whisky.

[UK]Hotten Dict. of Modern Sl. etc. (2nd edn) 104: Breaky-Leg strong drink.
[UK]Sl. Dict.