Joan's as good as my lady in the dark

‘Ioan in the darke is as good as my lady:’ Nay, perhapps better, such ladies there may bee.

1611, John Davies, "Vpon Englishe Prouerbs", Scourge of Folly, §386

Here is as good bread made as in France; and in the night Joan is as good as my lady; and unhappy is that man that is to break his fast at two of the clock in the afternoon and there’s no heart a handful bigger than another; and the stomach is filled with the coarsest victuals; and the little fowls in the air have God for their provider and cater; and four yards of coarse Cuenca cloth keep a man as warm as four of fine Lemster wool of Segovia; and when we once leave this world, and are put into the earth, the prince goes in as narrow a path as the journeyman; and the pope’s body takes up no more room than a sexton’s, though the one be higher than the other; for when we come to the pit all are even, or made so in spite of their teeth and—and good night.

1620, [Miguel de Cervantes], chapter XXXIII, in Thomas Shelton, transl., The Second Part of the History of the Valorous and Witty Knight-errant, Don Quixote of the Mancha. […], London: […] [Eliot’s Court Press] for Edward Blount, →OCLC

Night makes no difference 'tvvixt the Prieſt and Clark; / Jone as my Lady is as good i'th'dark.

1648, Robert Herrick, “No Difference i’th’Dark”, in Hesperides: Or, The Works both Humane & Divine […], London: […] John Williams, and Francis Eglesfield, and are to be sold by Tho[mas] Hunt, […], →OCLC, page 329

Sir Sim[on Addlepot]. Faith and troth I do not railly, I deal freely. / Flip [Lady Flippant]. This is the time and place for freedom, Sir. / Sir Sim. Are you handſom? / Flip. Jone’s as good as my Lady in the dark certainly; but men that deal freely, never ask queſtions certainly.

1671 March (first performance), [William] Wycherley, Love in a Wood, or, St James’s Park. A Comedy, […], London: […] J[ohn] M[acock] for H[enry] Herringman, […], published 1672, →OCLC, Act II, page 22

...when Henslowe notes Heywood's next play he has a little more respect for him; for, although the total was again but five pounds, three pounds on February 10, 1598/9 and the rest two days later, the dramatist on both occasions is Mr. Heywood. The only surviving fragment of the piece, ‘Jonne as good as my ladey’, may be a song in Γυναικεῖον with the burden 'What care I how faire she bee...

1931, Arthur Melville Clark, Thomas Heywood, page 12