Green’s Dictionary of Slang

any collection of supposedly like-minded individuals, e.g. the dirty mac brigade, middle-aged men with a taste for pornography.

1861		(con. 1840s–50s) H. Mayhew London Labour and London Poor I 244/2: People got ‘fly’ to the ‘shallow brigade’; so Peter came up to London.
1910		‘Doss Chiderdoss’ ‘The Protean Policeman’ Sporting Times 26 Nov. 1/3: Seeing how they trap the ‘lay the odds’ brigade, / That it doesn’t seem to work when there’s a murderer to find.
1915		G. Bronson-Howard God’s Man 181: Arnold became one of the Silk-Hat brigade.
1938		F.D. Sharpe Sharpe of the Flying Squad 249: He and some friends of the muffler brigade are said to have dined at a famous hotel in the Strand.
1963		K. Waterhouse Jubb (1966) 178: Hello, thought I, don’t tell me this is an invasion by the beatnik brigade.
1968		K. Brasselle Cannibals 326: Unless you want me to ‘yes’ you like your brown-nose brigade.
1979		S. King Dead Zone (1980) 177: It’s a gimmick for the blue-rinse brigade who read the weekly tabloids.
1982		G. Tate ‘Beyond the Zone of the Zero Funkativity’ in Flyboy in the Buttermilk (1992) 44: Great if you’re a breaking member of the boogie box brigade.
1989		J. Morton Lowspeak 32: Burglar Brigade – officers in prison who inspect the anus of a prisoner for concealed drugs.
2016		Guardian G2 12 Oct. 9/1: The heavy brigade [...] the bodyguard industry was booming.