I have NEVER read Philippa Gregory and now I assure you I never will. I cannot imagine taking such liberties with the lives of real historical characters, especially Queen Katharine of Arargon!! She was a woman of such honor and integrity and would never have lied about the non-consummation of her marriage to Prince Arthur. She would NEVER have lied to a marriage tribunal. A historical novel, like a good painting, is an artistic way of exploring the personality of a famous person or an aspect of their life in a way that one cannot in a non-fiction biography. There are freedoms one can take to emphasize certain aspects of the person or incident, but the author has the responsibility not to distort the facts of history in an unrecognizable way, or have a real person doing something that would have been totally out of character for him or her - like Philppa Gregory's Katherine of Aragon, or Carolly Erickson's new novel about Marie-Antoinette - just an excuse to write sex novels masquerading under the name of some queeen. I have no patience with trash.
My favorite novel about a Tudor queen is Ford Madox Ford's "The Fifth Queen" about Katherine Howard. It is meticulously researched and he makes the whole era come alive. He contends that Katherine H was not as loose as she is usually portrayed but very learned and lovely, which makes sense because Henry was usually attracted to clever women. She was descended from the Plantagenets and had more royal blood than the Tudors, but grew up in poverty, a bit unsupervised. Ford thinks that she was trying to reconcile Henry VIII to Rome, which is why she was framed. She signed a confession in order to make them stop torturing her maids and was beheaded. Henry really loved her and was destroyed by her death. It might be a bit dated for the younger crowd, but the writing is superb and very descriptive, very accurate.