Raven A. Nuckols' alternate history Had the Queen Lived: An Alternative History of Anne Boleyn is a most interesting conceit. Written in the form of a history rather than a fiction, it puts forward an imagined Tudor history in which Anne Boleyn was not tried and executed for adultery and treason, but instead lived to be Henry VIII's consort throughout his reign.
Nuckols takes as her point of divergence the fateful tournament held during Anne's pregnancy, in which Henry and his brother-in-law Charles Brandon faced each other in a friendly joust gone seriously awry. In 'our' history, Henry was injured and rendered unconscious - in fact, was initially thought to be dead. It is generally held that the shock of being told this was a major cause of her miscarriage of what appeared to be a healthy male fetus. Losing Henry's desperately wanted male heir left Anne vulnerable to both Henry's fears that this marriage too was cursed, and the political machinations that ultimately led to her trial and execution.
In Nuckols' alternate history, it is Brandon who suffers the near-fatal injury. Anne goes on to bear a healthy son and thus retains her position as Henry's wife and her influence over the governance of the kingdom.
The conceit is interesting, as are the ways in which Nuckols imagines Anne's continued influence would have changed the events of Henry's reign. As a thought experiment, it was enjoyable reading. One might not agree with the path Nuckols imagines for Henry and Anne during the course of a long and tempestuous marriage in which Anne actively sought to influence policy, but the effort involved in researching the possibilities is impressive.
Unfortunately, Nuckols is not the best of prose stylists - to put it mildly - and the book sadly lacks a good proofreader. The text is riddled with grammatical and typographic errors, incomplete sentences, and other issues that make reading a bit of a chore. But I persevered and was not unhappy to have done so.