Green’s Dictionary of Slang

(UK Und.) an establishment where transvestites can solicit conventionally dressed men.

1939		D. Maurer ‘Prostitutes and Criminal Argots’ in Lang. Und. (1981) 117/2: The slide. An establishment where male homosexuals dress as women and solicit men.
1941		G. Legman ‘Lang. of Homosexuality’ Appendix VII in Henry Sex Variants.
1965		Guild Dict. Homosexual Terms 42: slide, the (n.): An establishment where male homosexuals dress as women and solicit men. Some tape their genitals to themselves and have relations through the anus. Rare in the U.S.A. but easy to find elsewhere in the world.
1972		B. Rodgers Queens’ Vernacular 183: the slide (dated) establishment where men dressed as women solicit a male clientele.