Current knowledge
Unidentified
"Painted by Leonardo da Vinci", annotation added by Horace Walpole to the corresponding entry in his copy of George Vertue, Catalogue and Description of King Charles I's Capital Collection.. (1757) in the Surveyor's office, St James's Palace
Van der Doort 1639
Socrates ridden by his naked wife, another woman looking through the window, almost-life-size full-length figures
Sale Inventory c.1649-51
Walpole Society reference (1972):