Theirs is a love that has endured - rightly and wrongly - for more than 30 years.
By Jennie Bond
Royal affairs commentator
Charles and Camilla - 'soul mates'
It was at the start of the 70s that Charles and Camilla met at a polo match... where else?
The story goes that, in her raunchy, ribald way, she went up to the prince and said: "My great-grandmother was your great-great-grandfather's lover. So how about it?"
Well if she didn't say it, she should have because it's a peach of a line.
How different history would have been if they'd recognised the strength of their feelings back then and married one another first time round.
It's unlikely that Camilla would ever have been as popular as the innocent and beguiling Diana Spencer, but I believe she would have been accepted as the Princess of Wales, and future queen.
As it is, after a lusty affair, Charles went off to the Navy and dithered - aware that Camilla was not the "virgin bride" he felt he was obliged to seek out.
And Camilla fell back into the arms of her dashing cavalry officer lover, Andrew Parker Bowles.
Charles was bereft, but eventually wooed and wed Diana.
Only Charles and Camilla know the truth about how long they were faithful to their respective partners.
The prince certainly remained close to Camilla and her husband. Indeed he became godfather to their son, Tom, in 1974.
And there's no doubt that, a decade later, as his marriage to Diana began to implode, the only person who could truly comfort Charles was Camilla.
It was during those difficult - and eventually tragic - years that the prince focused on what for him became a fundamental but simple fact: whatever other sacrifices he might have to make, Camilla was "non-negotiable".
It was a powerful, uncompromising statement - and one that he has stuck to rigidly in the face of parental and public disapproval.
Diana, Princess of Wales, said Camilla 'deserved recognition'
Camilla is his soul mate. She understands him, panders to his needs and sympathises when he feels the world is against him - which is often.
They share a love of the countryside, of hunting and dogs, of walking in the rain and gardening.
After so many years of friendship and love, they are like a pair of comfy old slippers together.
Divorces happen. They are never pleasant, but most of us get a second chance of happiness.
Why should Charles and Camilla be any different? In middle age they are embarking on a marriage they should have begun three decades ago.
They have travelled a difficult, dangerous and sometimes devious road.
Their relationship has rocked the monarchy and caused a great deal of unhappiness to others.
Now as they put their house in order, their wedding plans have been dogged by the sort of bad luck you wouldn't wish on your worst enemy.
The past is over. Diana cannot be brought back or replaced. Even she accepted that Camilla was the love of Charles's life - in fact she once told me that she thought Camilla had been loyal and discreet and deserved some form of recognition.
Well, now she's going to get it. As the years roll by and we get more used to seeing the Duchess of Cornwall at Charles's side, she may eventually earn the recognition I think is hers by right: to be called Queen Camilla.