Weir acknowledges that the novel exerts a tremendous influence over peoples' idea of who Katherine was. Anya Seton made "impressive and commendable" efforts to get her facts right but it is not a valid portrayal of the historical Katherine Swinford. Seton applied Freudian Psychology in determining reasons for her characters behaviour but the morality of the book is very much that of the 1950s and not of the 1300s. A marriage based on love is a concept foreign to the 14th century mind.
"Katherine" is essentially a romantic novel riddled with romantic cliches- unrequited love, cruel conflict and lonely exile yet it has even been listed in the bibliographies of works of historical non-fiction, resulting in it achieving more credibilty than it deserves.
(personally, I still love the book but recognise it for what it is- a delightful old favorite!)
For me, 2 of the most dramatic parts of Seton's novel are;
Blanche, Duchess of Lancaster's death from Bubonic Plague at Bolingbroke Castle.- In reality, Blanche died at Tutbury Castle one month after the birth of her 3rd daughter, Isabella. This would suggest that Blanche had contracted Puerperal Fever.
Katherine barely escaping with her life when The Savoy is burned to the ground during the Peasants' Revolt........Katherine was almost certainly NOT there!
Katherine married Hugh Swinford certainly before 1365 and probably in 1362. This puts Katherine's age at around 12-15 years old at the time of her first marriage. the children of the marriage were; Margaret (professed as a nun at Barking Abbey), Blanche, Thomas and ? Dorothy.
There are indications that John of Gaunt had symptoms of a Venereal Disease and it was this illness that ended his life. Symptoms alluded to were intermittent attacks of illness in the late 1390s, putrifying genitals and blindness. This is not conclusive but Weir speculates that this was in fact, Gonorrhoea (Syphillis then unknown in Europe and was thought to have been introduced from the Americas in the late 15th Century)
Anyway, Weir points out that nearly every monarch in Europe was/is descended from Katherine..including Queen Elizabeth II and Diana, the late POW.
She also lists Sir Winston Churchill.
Alfred, Lord Tennyson.
Bertrand Russell, and 5 American Presidents as descendents ; George Washington, Thomas Jefferson,John Quincy Adams, FDR and George W Bush.
I cannot recommend Weir's book highly enough, it really is well worth the money. It has lots of notes, references and sources.