Green’s Dictionary of Slang

(gay) a good-looking, young homosexual.

1932		‘R. Scully’ Scarlet Pansy 333: The others present pointed her out as une belle, the same expression which is used so much in Baltimore and New Orleans.
1947		(con. 1944) J.H. Burns Gallery (1948) 140: What a town to cruise this is. All the belles in the States would give their eyeteeth to be in Naples tonight.
1949		‘Swasarnt Nerf’ et al. Gay Girl’s Guide 3: belle: Used with various connotations, such as 1) any homosexual; 2) a young, flashy and possibly beautiful homosexual. Often used interchangeably with queen.
1961		‘Lou Rand’ Gay Detective (2003) 90: He plays too damned rough! Did you hear about that belle he beat up.
1972		B. Rodgers Queens’ Vernacular 30: belle (obs, ’30s) 1. another homosexual ‘Just how many belles did you invite to my party, hon?’.
1985		K. Vacha Quiet Fire 174: There were the ‘belles,’ the piss-elegant queens.