Vortigern [Gwrtheirn in the Welsh] was left holding the bag. He is blamed by later writers as being responsible for inviting those folks we call "Anglo-Saxons" to our island. Some present day writers believe that "Vortigern" which means "high king", was actually the name given to many individuals. Thus it was a symbolic name and not actually the name of one person. The Welsh however give a detailed genealogy of this "high king", and I give it as recorded in Heraldic Visitations of Wales and Part of the Marches by Lewys Dwnn, Vol. I, p.xv. Vortigern is 11th in descent from Beli Mawr. The founder of our Jones linage in Wales was 16th in descent from Vortigern. From Beli to Vortigern was roughly 400 years. The eleven generations would average 400/11= 36.36 years per generation. From Vortigern to Tudor Trevor was about 550 years, thus 550/16= 34.38 years per generation. Not a long lifespan, but for the time peroid the figures fit pretty well.
The genealogy in Dwnn is given as follows: Gwrtheirn Gwrthenau [called in English Vortiger]
his son: Cyndeirn : his son : Rhudd Fedel frych : his son : Rhydwf : his son : Pasgan : his
son: Cadell Dehurnllue: his son : Gwnfiw frych: his son : Gwnnan: his son : Gwriawn: his son:
Biodderch: his son : Bywyn: his son: Gwaethiawe: his son : Gwrgenaw: his son: Cadfarch: his
son Member [Ynys]: his son : Tudor Trefor!
What a list of names and spellings. This is the beginning of our JONES family lineage, of course holding the bag.