I wouldn't be at all surprised to discover that this is close in terms of personality to the way Margaret Beaufort really was. The almost forced and certainly excessive piety, the steadfast refusal to accept another viewpoint, and certainly the obsessing over her son. Interesting they did manage to forge such a close relationship, though few have suggested in my studies that it was this type, seemingly lacking a certain humanity, for lack of a better term. 
 Philippa Gregory takes elements from her life and gives them an interesting spin--case in point, the discussion of having a dream that caused her at her tender age to end her 1st betrothal. In later life, she told her confessor that she had indeed had such a dream. Always thought it was a bit suspicious, myself. And as another reviewer commented, there are a couple errors--Edmund Tudor had no claim to the English throne since his mother was only Henry V's consort, for example. Strong links to the king, yes, but no claim to the title. Maybe one of the reasons the Tudors were valued on the Lancastrian side--strong supporters who could be counted on to not try for it. 
 I look forward to the next book.