Finished reading on 3/12/09:

MISTRESS OF THE MONARCHY: THE LIFE OF KATHERINE SWYNFORD, DUCHESS OF LANCASTER, by Alison Weir, 2009.

A good readable biography about Katherine Swynford, the woman who became the mistress of John of Gaunt (son of Edward III), bore him 4 children, married him as his third wife, and became an ancestress of all British monarchs beginning with the Tudors. Most of what I'd known about her before was from the novel Katherine, by Anya Seton. Good details of life in 14th century England; but facts about her seem so skimpy that there's lots of perhaps and probably and maybe used, which bugged me after a while. Good illustrations, family charts have some typos, notes, etc.