Once secure on the throne, King Henry VII sent a team to Wales which included a priest, a bard, and several others to research the Tudor ancestry from local records. Where-in they produced this geneology:
01. ARTHUR, King of Britain 495/504/507-538
02. Amhar [Anir; Enir] (d517)
03. Cadrod "Calchvynydd" (d556)
04. Yspwys (Esbwys), Lord of Ercing [Ergyng] (d581)
05. Cyngu "Carcludwys", Lord of Ercing (d624); he married Tegau, the daughter of Tudor “Mawr” of Brittany, the mother, not wife, of Alltu “Redegog”.
06. Alltu "Redegog", Lord of Ercing
07. Yspwys, Lord of Ercing
08. Mwyntyrch, Lord of Ercing
09. Yspwys, Lord of Ercing
10. Manan, a Welsh noble
11. Mor, a Welsh noble
12. Elvyw (Elfyw) (Eiluyw; Aildyw; Elevan), a Welsh noble
13. Kynan (Cynan), Lord of Clwyd [Denbigh]
14. Marchudd, Lord of Rhos, the head of one of the “Eight Noble Tribes” of Wales, resided in Denbighshire
15. Kerwit (Karwedh; Corwedd), Lord of Brnffenigl (Brynffanigl) [Abergele]
16. Senylt (Siaset) (Iasedd; Iaseth) (Iassedd) (Jafsedd) (Jafeth), Lord of Brnffenigl; = Nest
17. Nethan (Methan) (Inethan), Lord of Brnffenigl
18. Edred (Edryd; Edryt), a Welsh prince
19. Idnerth, Lord of Brnffenigl
20. Gwgon (Gwgawn), Lord of Brnffenigl; = Nest
21. Iorwerth, Lord of Brnffenigl; = Gwenllian, dau of Rhirid ap Pasgen
22. Kendrig (Cynwrig; Cynfrig), Lord of Brnffenigl; = Yngharad
23. Edynfed "Fychan", Lord of Brynffenigl [Abergele] & Seneschal of Gwynedd, d1246; =1 Tangwystl, dau of Llywarch ap Bran, Lord of Menai; =2 Gwenllian, dau of "The Lord Rhys", Prince of Deheubarth; had issue by 2nd wife
24. Gronwy (Goronwy), Lord of Tref-Gastel, d1268; = Morfydd, dau of Meuric, Lord of Gwent
25. Tudor "Hen", Lord of Penmynydd, d1311; = Angharad, dau of Ithel "Fychan, Lord of Englefield
26. Gronwy (Goronwy), Lord of Penmynydd, d1331; = Gwervyl, dau of Madoc ap David, Baron of Hendwr
27. Tudor "Frychan", Lord of Penmynydd, d1367; = Margaret, dau of Thomas ap Llywelyn, Lord of South Wales
28. Maredudd, a Welsh noble, d1406; = Mereditt, dau of David Fychan [ap David Lloyd], Lord of Anglesey
29. Owain Tudor, a Welsh squire, 2nd husband of Catherine of France, d1461
30. Edmund, Earl of Richmond, d1456 [= Margaret, the English heiress]
31. HENRY VII, King of England, exactly 30th in male-line descent from King Arthur, the ancestor of all succeeding English monarchs including Elizabeth II .
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I doubt the veracity of the linage - Henry VII just murdered the rightful King (Richard III) at Bosworth, he had good reason to produce such a family tree.