Green’s Dictionary of Slang

band of hope n.1

(Aus.) lemonade [the Band of Hope, formed 1847, was a temperance society].

[UK] ‘Drinks and Drinking in Australia’ Town Talk 19 Mar. 547: A band of hope ... Lemon syrup.
[Aus]North. Times (Carnarvon, WA) 24 Sept. 2/6: Band of hope: Lemon syrup.