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Prince Charles first met Camilla Parker Bowles in 1970. In one of the earliest pictures of the couple together, they are seen talking during a break in a Polo match.

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The Prince of Wales' relationship with Mrs Parker Bowles has spanned four decades.

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Here she is seen walking with the future princess Diana Spencer at Ludlow racecourse in 1980, in which the prince was competing.

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Princess Diana blamed the collapse of her marriage to Prince Charles on his relationship with Mrs Parker Bowles.

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The Prince of Wales and Mrs Parker Bowles appear together in public for the first time leaving the Ritz Hotel in London in January, 1999 after attending the 50th birthday party of Camilla's sister, Annabel Elliott.

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The Prince and Mrs Parker Bowles walk through to the Gala Dinner at The Princes Foundation in London, in June, 2000, to mark the official opening of the newly-restored headquarters of the Prince's Foundation.

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The Prince of Wales gets a kiss on the cheek from Mrs Parker Bowles, as he arrives at Somerset House in London in June 2001 at the 15th Anniversary reception, for the National Osteoporosis Society.

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The couple's public appearances have become more regular in recent years.

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In one of their most recent public appearances together, the Prince of Wales and Mrs Camilla Parker Bowles arrive at the Royal Gala in aid of Buxton's historic Opera House, in January.

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On Thursday, the couple hosted a dinner at Windsor Castle, their first public appearance since the announcement of their engagement.

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Mrs Parker Bowles showed off her platinum engagement ring which, consisting of a square diamond surrounded by three diamond baguettes, is a Royal Family heirloom. It reportedly belonged to Charles' late grandmother, the Queen Mother.