FOR nigh on 10 years, Princess Diana lived with the knowledge that there was a third person in her marriage.

Her distress at this situation was evident to anyone who saw her and to all those who knew her, years before she made it public in that interview with Martin Bashir.

It poisoned her days, haunted her nights and robbed her of the chance to achieve all that she wanted to as a wife, mother and working Princess.

So how appropriate then, that 10 years after Diana died in that car accident, Prince Charles has another wife with a pinched, drawn appearance, uncertainty etched on her face, living with the embarrassment of being constantly humiliated by another woman.

Camilla's statement on withdrawing from yesterday's Diana memorial service said: "On reflection I believe my attendance (at the memorial service) could divert attention from the purpose of the occasion which is to focus on the life of Diana."

But it was her face, like thunder but with a studied weariness that told the real story. Yes, she betrayed fury with her pompous husband, whose apparent selfishness and lack of understanding of the public mood has again led to her look ridiculous in public. But her face, pictured as she travelled to church in Scotland, also bore a horrified realisation, too. How long, she seemed to be saying, will this go on for? How long will I have to be made to feel this way?

The answer is probably forever.

Camilla's got everything she ever wanted: her Prince, her palaces, her position in society and all the money and servants a person could wish for.

Yet she is not secure and no wonder.

Like Diana before her, Camilla Cornwall has finally woken up to the fact that there are three people in her marriage - and one of them is the ghost of the beautiful, artful woman she wronged and who is now seeing her off, big-time.

Friends claim she is "humiliated and depressed" by the situation that erupted this week and that she's been tearful and traumatised'. At last, perhaps, she's beginning to realise how Diana must have felt.

What goes round comes round and the irony of this situation cannot have failed to pierce even Camilla's elephant hide.

The justice of it probably has, though.