I have made a start on the song - perhaps others would like to continue it?

Camilla and Charlie were lovers
Lord how they did love
Swore to be true to each other
No matter who they had to shove

She had a man
And he had his throne

Camilla was an old nag
Many times round the track
Well Charlie he didn't care
But he needed a young brood mare

He had a choice
But he wanted it all.