Queen Elizabeth II's only daughter, Princess Anne, is believed to have a close relationship with her sister-in-law, Queen Camilla.
But a little lesser known fact is that in the early 1970s, the Princess Royal was romantically linked to the man who would end up giving Camilla Shand her famous last name in marriage: Parker Bowles.
The Channel 4 documentary The Real Princess Anne sees experts delve into the press interest around the young Princess' love life in the Seventies, the Express reports.
It looked at some of Anne's early lovers, particularly her relationship with Andrew Parker Bowles, which would become an awkward “love quadrangle” between Anne, Andrew, Camilla and then-Prince Charles.
Royal experts claim that Anne and Andrew dated for "some time" but a now expired royal rule known as the Act of Settlement 1701 prevented their relationship from going any further.
The act ruled out any Catholics or their spouses becoming monarch and, with Anne fourth in line to the throne at he time, this ruled Andrew out completely.
The narrator said: “Most of the press pack were far more interested in the company she kept and whether they could marry her off.
“Would it be the Olympic gold medalist Richard Meade, who shared her passion for riding, or more intriguing, the 26-year-old Andrew Parker Bowles, not yet married to Camilla?
“He and Anne were often seen together, but he was a Roman Catholic and for a royal that effectively put marriage out of the question.”
The Act of Settlement was done away with in 2013 after the introduction of the Succession to the Crown Act.
It removed the historical disqualification of a person who married a Catholic from the line of succession and removed the rule of those outside the first six people in line to the throne having to ask permission from the Sovereign to marry.
The Act also removed the male primogeniture which prioritised sons over daughters in the line of succession.
However, by then of course, both Anne and Andrew had long moved on with their separate lives.
The princess went on to marry Captain Mark Phillips in 1973 with whom she had two children with, Peter Phillips and Zara Tindall, who have given her five grand children between them.
However, Anne and Mark's marriage did not work out and ended with a divorce in 1992 with the royal going on to marry the Queen's Equerry Commander Timothy Laurence that same year.
Meanwhile Andrew married Camilla in 1973 and they also had two children together, Tom Parker Bowles and Laura Lopes.
Andrew and Camilla divorced in 1995 after they both had affairs, which also led to the separation of Princess Diana and the then Prince Charles, as the now King cheated on the Princess of Wales with Queen Camilla.
Their relationship was reportedly resparked in 1986, with Diana and Charles announcing that they were separating in 1992, before it was formally confirmed in 1996.
King Charles and Queen Camilla never officially tied the knot until in 2005, with Andrew remarrying Rosemary Pitman in 1996 who he remained with until her death in 2010.
However, despite their history, Anne and Andrew are believed to remain good friends to this day.
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