Green’s Dictionary of Slang

effeminately homosexual.

1903		Ade People You Know 41: Nearly every high-speed Bachelor in Town had been forbidden [...] The kind that Mother approved were of the Lilac Division with White Puff Ties.
1962		K. Amis letter 14 Dec. in Leader (2000) 611: He can be detected by his sneers at the ‘lilac establishment’.