Green’s Dictionary of Slang

(Polari) a cubicle in a public lavatory, used for gay sex.

2007		W. Ings ‘A Convenient Exchange’ in Public Space 3 18: A lockable door was known as a brandy latch, but the door itself was called a trade curtain.
2019		P. Baker Fabulosa 290/1: brandy latch, a toilet cubicle.
2023		R. Milward Man-Eating Typewriter 108: [T]he manky pogi brandy-latch in the Holloway Road. Khazi with the glory-hole.