Thursday was a day to celebrate British book publishing in London, so it was only right that the event should bring together two reigning monarchs in their respective fields: "Harry Potter" author J.K. Rowling, 35, and Her Royal Majesty Queen Elizabeth II of England, 74. Meeting at the offices of Rowling's publishers, the Queen, showing some familiarity with Rowling's four "Potter" books, was quoted by Reuters as saying with typical British understatement, "I am told that children have started to read them. They are certainly popular with one of my grandchildren." She did not specify which. Rowling did note that the Queen's son, Prince Charles, "knows the books well and likes them." As for Rowling's exalted stature in book publishing, her tales of Potter have sold more than 60 million copies in 200 countries and are credited for reviving a love of reading among children, even in America. Speaking for her royal self, Queen Elizabeth told Rowling and her publishers, "I was a voracious reader when I was a child. It stood me in good stead because I read quite quickly now and I have to read a lot."