Entry revised for OED Online

chattering classes (occas. also in sing. chattering class) freq. derogatory, members of the educated metropolitan middle class, esp. those in academic, artistic, or media circles, considered as a social group freely given to the articulate, self-assured expression of (esp. liberal) opinions about society, culture, and current events.
 
  1980 F. JOHNSON in Now! 21 Mar. 48/1 The peculiar need for something to be frightened about only seems to affect those of us who are part of the chattering classes. 1990 R. CRICHFIELD Among British vii. 457 The old Britain of Eton, Oxbridge, the land, and the Guards, allied with a chattering class of literary intellectuals, so invaluable when it came to running an empire, is deadly when it comes to bringing the country into the 1990s. 1994 Daily Mail 18 July 8/2 A battle between Middle England—the sensible heart of the British middle classes—and Islington Person, the politically correct voice of the chattering classes. 2000 Sunday Times (Johannesburg) 4 June (Mag.) 6/1 For a day or two, the chattering classes were treated to speculation about government intervention.