John, I understood mtDNA to be only trackable through the females, and unless we've been seriously misled, Richard III was gender bio male ?
Would have to be his mama, from those two modern females to Richard III's mother ... ah, Cecily Neville (1415-1495)
Have to take it on faith that Richard is the proven (DNA) fruit of the union of Cecily and whomever .... NOT a student of English British etc history ...
Paper trails are so satisfying, you know, you track it down, lay it out, type it up, get a printout and voila everyone related knew where they fit into the picture.
And then along came DNA ... and skeletons, SECRETS, started falling out of closets, the rafters, or being dug up in basements, hauled out of the sheds long abandoned, or sent anonymously in plain brown wrappers to those who least expected such a thing ... and now you don't dare say you are descended from ... anyone ... unless you have that DNA proof. Best you can say anymore without that DNA is "So far as is known ..."