The portrait of Benedicta Milson is actually of Margaret Tudor (1489-1541), eldest daughter of Henry VII of England. To fit in with the story, the picture has been altered to include a treasure chest and a necklace around Margaret's neck. Margaret's right arm has also been moved to rest on the chest. Originally, both her arms were folded across her body, supporting a small monkey which is now partially floating in mid-air.
Aden Gillett plays Christopher Corby in this episode. He previously played the role of Ian Kent in episode 13.4, The Silent Land (2010).