1824, August 10, Charles Lamb, letter 350 to Thomas Hood, published in The Works of Charles and Mary Lamb, volume 6 Letters 1821–1842, edited by E. V. Lucas:
I design to give up smoking; but I have not yet fixed upon the equivalent vice. I must have quid pro quo; or quo pro quid, as Tom Woodgate would correct me. My service to him.
1876, February 24, unknown author, Daily Democratic Statesman, quoted by Chuck Parsons in “Pidge,” Texas Ranger, published 2013, →ISBN, page 185 in note 94 on chapter “Pidge and the Rio Grande Frontier”:
In Virginia they propose to tax each person who uses tobacco on the quo pro ‘quid’ principle.
1961–62, Humphrey Mynors, quoted in The City of London: A Club No More, 1945–2000, by David Kynaston, published 2001, →ISBN, part 3 “1959–70”, chapter 11 “Italian Motorways”, page 288:
Have they not conceded on occasion without getting any redeployment as a quo pro quid, knowing that they can always offload the cost on to the home market?
