Old Etonian banker Lord Tryon's voluptuous Australian-born wife Dale, for example, was often visited by Charles making what she used to call a 'comfort stop' on his way home to Highgrove.'He would ring out of the blue and say he would be passing by and would I mind if he popped in,' Lady 'Kanga' Tryon revealed in charmingly diplomatic language shortly before she died of blood poisoning following surgery in 1997.
For a start, Camilla knew that she would need to get away - and get away as often as possible - from the restricted and highly ordered royal life that he leads at Highgrove and in his other homes.
In particular Camilla, renowned for her domestic untidyness, would need to escape from Charles's obsessional neatness, especially over where and how certain things are placed around his homes.
'I'd make sure a whisky was ready for him, then we'd chat before making ourselves more "comfortable".' As the shadowy mistress of a married man, Camilla could have no complaints.
But as the wife - and now in her 60th year - things are markedly very different, especially as Charles is perceived in a broadly similar light to the late billionaire Sir James Goldsmith, who always had a mistress in addition to a wife and who famously declared: 'When you marry your mistress you create a job vacancy.' The general feeling among Camilla's friends, is that if that did happen, she could handle it.
We are used to the eccentricities of the aristocracy, and the single-mindedness of royalty, but the Duchess of Cornwall's insistence on retaining Raymill House as her personal 'bolt-hole' inevitably raises intriguing questions.