backstairs

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.

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; […]

Scandalous.