Although the move was shocking for the day, three of Her Majesty's children, Prince Charles, Princess Anne and Prince Andrew, would go on to divorce their spouses in the nineties.
In the Channel 5 documentary The Royal Family: Affairs and Infidelities, 44-year-old Margaret's relationship with 27-year-old Roddy Llewellyn has been understood as one of the great affairs within the royal family.
The documentary delves into the media frenzy surrounding photos of Roddy and Princess Margaret's time together on the island of Mustique, in 1976. The snap would become the catalyst for the very public and outrageous divorce in 1978.
Royal biographer Anne Sebba explains: “He was highly unsuitable, so these photographs were fairly dramatic really.
“Princess Margaret was after all the Queen’s sister, so what did this say about the Royal Family and their stability?”
In the documentary, the narrator notes of the divorce: “The divorce could be considered a landmark moment in royal history.
“Princess Margaret would be the first major royal to get divorced in over 400 years.”
Although the discretion resulted in the Earl of Snowdon and Princess Margaret's divorce, both parties were reportedly serially unfaithful throughout the duration of their marriage.
Editor of Majesty magazine Ingrid Seward explained: "In Princess Margaret’s day, it was still considered extremely shocking, basically because she was so close to the Queen.
“Here’s the Queen who is the head of the Church and here’s her sister who is getting divorced.”