In episode four, titled, "Annus Horribilis," the Queen and Prince Andrew have a candid conversation surrounding his marriage to Sarah Ferguson, Duchess of York, and a rather risqué set of photos including her and American financial adviser John Bryan. This event did actually happen, and it was a pivotal moment in Queen Elizabeth's "Annus Horribilis" year of 1992.
According to The Washington Post, Ferguson, who was separated from Prince Andrew at the time, was holidaying with Bryan in Saint Tropez in August 1992, when The Daily Mirror's photographers photographed the Duchess topless as she was being intimate with Bryan. Some photographs showed Bryan kissing her toes and foot, leading to a frenzy in the media and even more criticism of the already vulnerable monarchy.