Further more according to Mike Haseler on his Mons Graupius site all academics are barbarians.
'Academics are Barbarians!
(Why all etymologies are suspect)
But whilst it is easy to show that many iconic words of "Celtic"-Roman Britain can easily be derived from Anglo Saxon, this is not the same as saying that the Britains spoke Anglo Saxon. The reality is the whole area of deriving words and place names from ancient languages is highly suspect and clearly wasn't exactly honest - particularly when "possibly could" becomes "definitely is". The most obvious example of academic bias is in the derivation of the word "Barbarian".
First you need to know that historians during the age when all these etymologies were created were fed a diet of Latin & Greek and the British empire was likened to that of Rome. Second you need to know that the Romans called the natives (who did not shave like them) barbarians. If you go and look you will find a derivation of the origin of "Barbarian" such as:
Latin barbaria "foreign country," from Greek barbaros "foreign, strange, ignorant," from PIE root *barbar- echoic of unintelligible speech of foreigners (cf. Sanskrit barbara- "stammering," also "non-Aryan," Latin balbus "stammering," Czech blblati "to stammer"). (Link)
So "Barbar" was asserted as being like baby talk "dada". But what do we find if we go and look at a Latin dictionary:
barba: Beard
barbarinus: Barbarian.
It will also help you to understand why this etymology is not used to remember that a lot of academics who were teaching how the British Empire was like the Roman empire used to wear beards! So, they ignored the very obvious and almost certain derivation in favour of a completely nonsensical derivation from nonsense because they didn't like the implication that beards were barbarous. At the very least, even if it original derived from "nonsense" utterings, it certainly would have been understood by Latin speakers to mean "beardies" in the same way as we call people today "Skin-heads'''
http://mons-graupius.co.uk/index.php/ot ... -are-keltsOn this page of the site he argues at length that the British were not Celts (Kelts) and in other pages he argues that Druids and the name Druid are actually Germanic.
But as for what the Romans did for us, they left certainly and he quotes Nennius to tell us who they took with them and where.
'Indeed we have a good historical account from Nennius* which tell us that the Bretons derive from a "British" army which crossed with the British Roman Emperor Maximus to France about 388AD:
"The seventh emperor was Maximianus. He withdrew from Britain with all its military force, slew Gratianus the king of the Romans, and obtained the sovereignty of all Europe. Unwilling to send back his warlike companions to their wives, families, and possessions in Britain, he conferred upon them numerous districts from the lake on the summit of Mons lovis, to the city called Cant Guic, and to the western Tumulus, that is Cruc Occident. These are the Armoric Britons, and they remain there to the present day."'
Even today the Bretons call their French speaking neighbours in the east of Brittany 'Gallos' referring no doubt to their Gaulish origins and identity. But they never claim them as Bretons except in a geographical sense.
Here's a map of language distribution he has taken from wiki to support his ideas.

I imagine he is ruffling a feather or two north of the Windy Landa wall.