Even given the taboos both of the historical period and of the next several centuries of research into and writing about history, there is a fair amount of historical documentation of contemporary rumors and reports that King James I (played in this series by Tony Curran) was gay, or perhaps bisexual, giving a historical basis to this aspect of his depiction in "Mary & George." His close relationships with a series of male courtiers were often remarked-upon in letters and other documents of the day. Two of the men whom many historians agree were likely his lovers are depicted in this series: Robert Carr, 1st Earl of Somerset (Laurie Davidson) and George Villiers, Duke of Buckingham (Nicholas Galitzine); Sir John Oglander, a contemporary politician and diarist, wrote that James "is the chastest prince for women that ever was, for he would often swear that he never kissed any other woman than his own queen. I never yet saw any fond husband make so much or so great dalliance over his beautiful spouse as I have seen King James over his favourites, especially the Duke of Buckingham," and a Royal Navy officer, Edward Peyton, observed James "tumble and kiss [George] as a mistress" in view of the court. James I was the same King James who sponsored the translation of the Bible that is still known today as "the King James Bible," which is another reason that religious interests may have been eager to deny or expunge from history the possibility that James was gay or bisexual.
Tony Curran is credited as James I, even though he was James VI & I, as the first ruler of the joined Scotland (6th King James of Scotland) and England (1st King James of England).
Amelia Gething who plays Frances Coke Villiers was in another Starz show about royalty. She played Lady Ursula Pole Stafford whose parents were first cousins to Elizabeth of York, the mother of Henry VIII.