Green’s Dictionary of Slang

(orig. US) carping, negative criticism; thus used as a personification.

1888		Peterson’s Mag. vol. 92 107/1: Not the man with a grouch playing the anvil chorus, finding everything wrong and grumbling his days away.
1899		W.J. Kountz Billy Baxter’s Letters 20: Say, Jim, I’ve heard knockers in my time, but Estelle is the original leader of the anvil chorus.
1908		K. McGaffey Sorrows of a Show Girl Ch. ii: ‘No knocking or nothing; just sit and talk real friendly like.’ ‘That’s the idea and if anyone starts the anvil chorus they get the skiddo.’.
1911		S. Ford Torchy 160: ‘Who is that with you?’ He gets answers from the anvil chorus. ‘That’s the swindler!’ they shouts.
1914		‘Hugh McHugh’ You Should Worry cap. 10: It’s no secret conclave of the Anvil Association when I whisper them wise.
1919		Van Loan ‘Excess Baggage’ in Score by Innings (2004) 398: The anvil chorus was a dying whisper beside the knocking that came off in the next few days.
1926		Wood & Goddard Dict. Amer. Sl. 3: anvil chorus. A chorus of knockers or depreciators.
1941		in Sat. Eve. Post 17 May 18: The leader of the anvil chorus .
1952–3		Mad mag. Dec.–Jan. 18: What with Minx’s canaries chirping the anvil chorus [...] I won’t get a plug in edgewise.