^between the relative invisibility of even upper-class women in the historical record, the relative social invisibility of the "hired help" in general, and the minor detail that after about the 1200s homosexual acts were at least technically (actual enforcement was as usual highly variable) increasingly criminalised across Europe you'll be hard pressed for hard evidence as opposed to assorted tendentious slander - often about a political enemy's wife - and outright politically motivated fabrications. But already given the number of men and women charged with "unnatural acts" over the centuries, and the quite well-documented tendency for... indiscretions... between "upstairs" and "downstairs" it is a perfectly safe assumption that a decent amount of lezzing happened in the privacy of the ladies' quarters.