John and Bernard Stuart were brothers of James Stuart, Duke of Richmond and Lennox, who is one of the main characters in my novel The Winter Prince, set during England's tragic civil wars. Both these gentlemen lost their lives fighting for Charles I, as did their older brother George. I was familiar with this magnificent double portrait by Van Dyck but had never seen it--until I viewed works from Van Dyck's personal collection, currently exhibited as part of Painters' Paintings, a brilliant show at the National Gallery in London. It was touching to see it, as I could not help becoming fond of James Stuart when writing The Winter Prince.