A staircase at the rear of a building or one normally only used by servants and tradesmen.
Here I diſcovered the ſecret Cauſes of many great Events that have ſurprized the World, how a Whore can govern the Back-ſtairs, the Back-ſtairs a Council, and the Council a Senate.1726 October 28, [Jonathan Swift], “A Further Account of Glubbdubdrib. […]”, in Travels into Several Remote Nations of the World. […] [Gulliver’s Travels], volume II, London: […] Benj[amin] Motte, […], →OCLC, part III (A Voyage to Laputa, Balnibarbi, Glubbdubdribb, Luggnagg, and Japan), page 111:
1905, Ernest William Hornung, “The Spoils of Sacrilege” in A Thief in the Night, Other feet were already in the lower flight of the backstairs; but the upper flight was the one for me, and in an instant we were racing along the upper corridor […]
2
An indirect or furtive means of access or intercourse.
The straight-forward course, they say, would be to proclaim outright, instead of trying to bring it in by the backstairs.1934 March 27, “De Valera Move Hits Dignity Of Governor-General”, in Christian Science Monitor:
backstairs
adj
Etymology From back + stairs.
1
Secret or furtive.
[…] if some peers (I am very sorry they are not as many as they ought to be) set themselves, in the great concern of peers and commons, against a back-stairs influence and clandestine government, then the alarm begins; then the constitution is in danger of being forced into an aristocracy.1770, Edmund Burke, Thoughts on the Cause of the Present Discontents:
The danger of the situation was increased by the mischievous conduct of Alderman Townshend, who had been brought down to the House, pale and bandaged from a recent surgical operation, in order to pour forth a diatribe against female caprice and backstairs influence; […]1880, George Otto Trevelyan, chapter 8, in The Early History of Charles James Fox, London: Longmans, Green, and Co., published 1881, page 364:
1 more example
This backstairs visit was all about sex […]2004, Alan Hollinghurst, chapter 3, in The Line of Beauty […], London: Picador, →ISBN: