Sweden's Princess Lilian, the Welsh-born model who lived with her lover Prince Bertil for 30 years before they were married, has died at the age of 97, the Swedish Royal Court said in a statement.
"It is with sorrow that I have learnt that H.R.H. (Her Royal Highness) Princess Lilian is dead," Swedish Prime Minister Fredrik Reinfeldt said in a statement.
"A much loved and appreciated member of the royal family has now passed away," he added.
Born in 1915 in Swansea, Wales, Lilian May Davies was a Vogue model and married to British actor Ivan Craig when she first met Prince Bertil, the current king's uncle, in 1943.
Then engaged in wartime work making radios for the Royal Navy, she reportedly met Prince Bertil at a cocktail party for her 28th birthday. Reports about their first meeting vary, with some saying they met at a nightclub called Nuthouse while others that they met on the London Underground.
The two soon became lovers and she divorced her husband in 1945.
However, due to Sweden's strict royal succession rules -- which at the time did not permit a contender for the throne to marry a commoner -- King Gustav VI Adolph (the current king's grandfather) would not give his blessing to the union.
Prince Bertil's two brothers had already renounced their right to the throne by marrying commoners and the only heir, his older brother Crown Prince Gustaf Adolph, died in a plane crash in 1947.
With a strong possibility that Prince Bertil would have to act as Regent to the present King Carl XVI Gustaf, who was less than a year old when his father was killed, the couple did not marry. Instead, they lived together discreetly in a villa in the South of France.
By the time King Carl XVI Gustaf took the throne in 1973, times had changed. He himself was married to a commoner and the couple were finally permitted to marry 33 years after they first met, on December 7, 1976 at Drottningholm Palace Chapel.
Prince Bertil was popular in Sweden where he was dubbed "Prince Charming" by the media for his long romance with Lilian. He died in 1997 aged 84 with Lilian at his bedside.
Princess Lilian remained active in public life until her early 90s, attending the Nobel Prize ceremonies adorned in royal jewels. In 2005, at the age of 91, she stopped attending the ceremony, citing her advanced years.
In 2010, she withdrew from public life suffering from Alzheimer's disease. The couple never had children.
She was the oldest member of the Swedish royal family at the time of her death and, despite the problems that led her to wait more than 30 years to get married, was a fully integrated member of the Swedish Royal family.