Green’s Dictionary of Slang

(Aus.) a venereal disease clinic, thus blue-light outfit, a portable kit for personal treatment.

1918		in A.G. Butler Austral. Army Med. Services 1914-1918 (1943) III 158: ‘Early Treatment’ Depots have been designated ‘Blue Light Depots’. At night a blue light shows their position in every unit lines, and at Administrative Headquarters, London. No names or questions regarding identity are asked [Simes:DLSS].
1919		W.H. Downing Digger Dialects 12: Blue-Light—A prophylactic establishment.
1919		E.A. Rout Two Years Paris (1923) 20: The English, Australian and New Zealand Y.M.C.A. have agreed among themselves that vice must be kept dangerous. They have tried to have closed the Blue-Light Rooms [ibid.] 23: You had far better carry a blue-light outfit with you as a ‘town dressing’, in the same way as you would carry a ‘field-dressing’.
1924		(con. WWI) A.G. Pretty Gloss. of Sl. [...] in the A.I.F. 1921–1924 (rev. t/s) n.p.: blue light. A prophylactic establishment.
1944		L. Glassop We Were the Rats 85: I asked Eddie what the blue light on a tent behind the C.R.S. was for. [...] ‘That’s the blue light joint. On ya way back from leave ya go there. That’s if ya been doin’ the wrong thing. Haven’t ya seen them blue light outfits? They stop ya getting’ what ya shoulden get’.
1954		(con. 1940s) T.A.G. Hungerford Sowers of the Wind 28: We don’t want to get jacked-up, that’s what [...] We got no blue-light outfit with us [Ibid.] 198: ‘She’s clean, I suppose?’ ‘Yes. After the first time I didn’t go to the blue light. Nothing happened, or since’.
1990		R.G. Barratt ‘Who’s Jack of Robbo?’ in What Do You Reckon (1997) [ebook] I got the jack years ago and had to go to the VD clinic [...] the old blue light.
2000		Desdemona at www.asstr.org 🌐 Mama always said: some men weren’t worth pleasing. And a man with stock in the blue-light clinic was one of them.