Catherine de Valois’ first husband was Henry V, who was clearly the grandson of John of Gaunt. Edmund Beaufort, later Duke of Somerset, is traditionally regarded as Gaunt’s grandson as well, although his father may have been a legitimate Swynford.
Quite apart from the 1420s legislation banning royal stepmothers such as Catherine from remarrying without her adult son’s consent – and we know that she died before he attained his majority – this created an additional barrier of affinity in that her late husband and new partner were apparently first cousins. Such a marriage, quite apart from being illegal in England, would have required a dispensation. No wonder it was more convenient to portray her servant Owain Tudor as the father of her children.
See here for a further complication.
murreyandblue 
This presupposes we accept the theory (and it is still only a theory) that Beaufort was the father of Catherine de Valois’s elder children.
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Indeed but that case is now strengthened. How many children did she have? Different cyber-sources quote different numbers but we can only really rely on Henry VI, Edmund and Jasper “Tudor”.
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I must have missed something, strengthened by what?
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The necessity of hiding behind Owen Tudor because of the affinity between Catherine and Edmund. This is the principle that invalidated Henry VIII’s first two “marriages”. Canon law required a dispensation for one to marry a close relative of a previous partner (eg Arthur “Tudor” and Mary Boleyn).
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Yes, but as I said originally, this is only valid if we accept the theory that Catherine and Beaufort were a couple. As yet, this theory has not been proved and thus must remain for the moment speculation.
Even JAH has stopped using quotation marks round the word Tudor, so perhaps we could all follow suit?
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Well, there is quite a bit of evidence for it and none against.
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