Green’s Dictionary of Slang

mile and a quarter n.

(Aus.) water.

1967

Aus. Women’s Wkly 18 Oct. 2/3: It was there I heard about a gay-and-ten, which is cockney rhyming slang for whisky-and-water. ‘Gay’ is for ‘gay and frisky’ (whisky) and ‘ten’ for ‘ten furlongs’, which is a ‘mile and a quarter’ (water).