The Palace - Season 1 Episode 8

Eleanor has discovered that Queen Charlotte had an affair many years ago, the dates of which mean that Richard might not actually be the rightful King. She leaks this to the Archbishop, who in turn questions Iain, who is forced to ask Queen Charlotte about these delicate matters. The Queen reluctantly admits to her son that it could be true. He might be illegitimate, which forces Richard to take a DNA test to prove his paternity.