Green’s Dictionary of Slang

thespian n.

also West End thespian
[pun on SE + ? alleged prevalence of homosexual men in theatre]

a lesbian.

[US]B. Rodgers Queens’ Vernacular.
[US]Maledicta VI:1+2 (Summer/Winter) 136: Jokes about thespians and tomboys and tit-kings were heterosexual [...] first.
[UK]B. Dark Dirty Cockney Rhy. Sl. 106: West End thespian lesbian.