“There are thousands of prints by Rembrandt Van Rin (to name but one artist) depicting sexual intercourse, so at least one such print will figure in all the important State and private collections [….] I understand that the Queen has some highly erotic work by Fragonard.”
From a story about a 1970 obscenity case involving John Lennon’s sketches of himself and Yoko having sex.
A few Fragonards (fairly safe for work, though The Bathers could be borderline if you work with utter prudes. A deeper search turned up this piece, with a sleeping woman dreaming, or inviting, a trio of horny cherubs bearing ‘phallic objects’.)