Diana, Princess of Wales, was a commodity and she had a pretty shrewd idea of her own value. "You see yourself as a good product that sits on a shelf and sells well," she said in a famous confessional BBC TV interview in 1995. "And people make a lot of money out of you."
They still do. When she was alive, everyone wanted a piece of Diana. Photographers chased after her smile, newspapers hung on her words, her fans bought anything that would get them that little bit closer to the fairy tale. And...