"........ the longer one goes back in history the less one knows for sure......." is what I wrote in my entry of January 14th about Sir Thomas More. The notion that the less one knows the further one goes back, came out of a little book I read a couple of years ago, called, "The History of Britain: The Shocking Truth About the English Language", by MJ Harper.
This book says, in so many words, that what we learned in school about the origins of the English language is rubbish. We're told that English came out of the language of the Anglo-Saxons who invaded Britain in around 450 AD. Britons in the path of the conquering Anglo-Saxons fled west to where Wales and Cornwall are now, and took their Celtic language with them. Those Britons not fleeing, while they didn't abandon their homes, did abandon their Celtic language for the Anglo-Saxon tongue, which became the English of today.
The trouble with all this is that abandoning one's home language en-masse for the language of an invader isn't what people normally do. While they may feel the need to learn the invaders' language in order to make a living, they'll continue to speak their native tongue at home, and will ensure that their children speak it too. Hence the native tongue survives down the generations.
History over the last five-hundred years has shown this to be true. Why, then, should this dynamic have been any different when the Anglo-Saxons invaded Britain?
Unless it can be shown that the Anglo-Saxons killed all the Britons in the areas they conquered, so that there were no Britons left in these areas to speak Celtic, then Celtic would have survived in England.
It is more likely that Britons in the path of the conquering Anglo-Saxons already spoke English, so that the English we speak today came out of the English that Britons in the path of the invading Anglo-Saxons spoke then.
The reason for the rubbish we all learned in school about the origins of the English language was, no doubt, because not much is known for sure about what went on in 450 AD when the Anglo-Saxons invaded, because it was so long ago.