Green’s Dictionary of Slang

the gentleman’s lavatory.

1938		G. Greene Brighton Rock (1943) 233: He looked round for a Gents’ sign – ‘I just got to go – an’ wash’.
1944		J. Cary Horse’s Mouth (1948) 290: He can always go to the public gents’ down High Street.
1957		K. Amis letter 19 Feb. in Leader (2000) 504: Pissed in Gents, failed to shake cock enough and drenched left leg.
1964		P. Larkin ‘Essential Beauty’ in Whitsun Weddings 42: The boy puking his heart out in the Gents.
1970		G.F. Newman Sir, You Bastard 227: James went out to the gents.
1974		P. Larkin ‘Livings’ in High Windows 37: A beer-marquee that / Half-screens a canvas Gents.
1989		M. Amis London Fields 24: It ended with Keith carefully kicking selected areas of a fallen figure wedged into the doorway to the Gents.
1997		D. Farson Never a Normal Man 228: A ‘gents’ called Adam’s Boudoir.
2000		Observer Screen 6 Feb. 24: They can always go and read the gents’ walls in the pubs of Walthamstow.
2001		Indep. on Sun. Rev. 15 Apr. 53: Oh for God’s sake, where’s the gents?