The late Duke of Savoy's grandmother referred to in the Van der Doort entry would be Margaret of Valois (1523-1574). This sitter is identified as her contemporary, Christina of Denmark.

"Now in the collection of Mr H Walpole", 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