1813 2 Sept. 3/1 To counteract these rumours, Savary, the notorious Police Agent, had thought it necessary to circulate a sort of Bulletin.
1930 G. B. Shaw p. xvi Proletariats are never revolutionary, and..their direct action, when it is controlled at all, is usually controlled by police agents.
1987 R. Hall (1990) ii. xxxviii. 205 Was he a police agent? A rapist? A plainclothes priest?