Princess Diana, resigned Saturday as board chairman of Britain's National Gallery.Hall, who subsequently rose to the top job at the BBC, was heavily criticized in a report this week for a botched inquiry into how journalist Martin Bashir obtained the blockbuster interview.In a statement, the 70-year-old said his continued presence at the gallery would be a "distraction to an institution I care deeply about.”“As I said two days ago, I am very sorry for the events of 25 years ago and I believe