Charles is not the only child of Queen Elizabeth having marital problems.
Charles is not the only one with marital problems. In the previous season, it was alluded that Princess Anne (played by Erin Doherty in season four) is unhappy in her marriage to Olympic equestrian rider Mark Phillips (Geoffrey Breton).
In episode four, Anne confirms to her mother that she has been having an affair with her protection officer, but the Queen offers little help other than to tell her to persevere. In real life, Anne got divorced in 1992 and married the protection officer, which is likely to play out in season five.
Anne’s brother, Andrew, also got divorced during the 1990s. In season four, we see Prince Andrew (Tom Byrne) finally settle down with Sarah Ferguson, but things might get rocky during the fifth season.