"like the head of the dead king when they opened the coffin at Windsor"
St. George's Chapel, Windsor
Creative Commons AttributionSt. George's Chapel, Windsor - Credit: Christian Bortes, Wikimedia Commons

This rather macabre reference may refer to the discovery of the well-preserved head of King Charles 1st. (who was executed in 1649) in the vault of King Henry Vlll at St. George's Chapel Windsor in 1813. The examination of his decapitated head was supervised by the physician Sir Henry Halford.

Another tomb containing the skeleton and hair of Edward lV*(1442-1483) was discovered in St. George's Chapel in 1789. The opening of the tomb was supervised by the architect Henry Emlyn.

(*scroll down on this website to the heading, The Tomb of Edward lV