Unless you are a devoted student of history, the answer may be no. But what they share, along with (briefly) Catherine of Aragon, is that they were at one time all the Princess of Wales.
For the vast part of history, the title now bestowed on Catherine Middleton, wife of Prince William, meant a figure destined to be largely forgotten.
They were always “just” the wife of the Prince of Wales, apart from the aforesaid Gwenllian, the only Welsh woman to have been given the title in her own right by her father Llywelyn, last native Prince of Wales.
If Catherine was coming to this role at almost any other time, it would be unremarkable to be named Princess of Wales.
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But the last woman with the title was Diana Spencer, her late mother-in-law who became probably the most photographed woman in the world.
It’s a tough act to follow. Diana’s life – from the “fairytale” wedding later revealed to be a loveless union, to her high-profile divorce and death in a 1997 Paris car crash aged 36 – had all the elements of a modern-day Greek tragedy.
The ongoing public adoration of the “people’s princess” made it impossible for Camilla Parker Bowles to consider using the title when she married the then Prince of Wales in 2005, sticking to the lesser rank of Duchess of Cornwall.
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Cathrine Middleton at her graduation from the University of St Andrews in Fife
And now it is Catherine’s turn, for Catherine she has become. Newspapers like to forget they called her “waity Katie” during the years between the couple meeting in 2001 and their engagement in 2010.
But those years that followed the first encounter at St Andrews gave her what Diana never had: a chance to edge her way slowly towards a royal role she assumed on marriage, a decade older at 29 than Diana had been.