In this book, unlike in most of Alison Weir's previous, she employs endnotes, but feh, I cannot agree with her conclusions. She overlooked and elided earlier points that she made when she wanted to draw a different one.
I can believe at least two things: that Isabella was not an accessory to Edward II's murder, and that Edward II, though murdered, was not murdered with a red-hot iron shoved up his bowel. I can stretch to recognize the remote possibility that he escaped and lived out his life quietly elsewhere (though she says once that he left Ireland for fear of being recognized and returned to England, where, you know, no one would recognize him).
I cannot quite embrace the idea that he escaped to the Continent and had audiences with the French king and the pope and died a hermit and no one in either court ever mentioned a word of this in their own records. And the suggestion that he ventured from seclusion to visit England once as "William de Galey" (William of Wales) and see his son is entirely over the top, as is the fancy that his monastery shipped his embalmed corpse to Albion when his natural death occurred.
An example of Weir's seeing only one possibility: When Edward II possibly escaped, he possibly killed a porter, whose body conspirators possibly dressed as his. Weir alleges that since Isabella would not have wanted to be lie alongside a porter, her willed intent to be buried in his tomb indicates she knew it wasn't the commoner's body but that of her husband, finally parcel-posted from Italy. Much nearer-fetched is the likelihood that it was Edward's body all along, or that if it wasn't, she didn't know it; or if she did know it, she also knew she should keep up appearances even in death.
What intrigues me is that, according to the evidence Weir has compiled, no one in any court in England, Paris, Hainault, or Avignon (where a version of the pope was in the 14th century) wrote anything about Isabella's sexual relationship with Mortimer, even in the veiled terms they weaseled about Edward II's homosexuality. And for a woman fertile enough to bear four healthy children to a man who preferred men not to bear, to a man who preferred her, even a pregnancy that lasted long enough to show, is odd. Weir excuses this with her being 30 and more, but Henry II thought Eleanor of Aquitaine at 27 was still a good enough dynastic bet to shatter the commandments on the spot "The Lion in Winter"for.