The Anglophile, Bill Bryson, spreads the word a bit in his book "Mother Tongue-The English language."
But describing KIng Arthur as 'semi-legendary' is only half true, if we take the term 'legendary' to mean fabulous or mythical. Also, his remark 'Many English place names are Celtic in origin (Avon and Thames, for instance)' depends on what is meant by 'many', and his examples are odd. Over most of England the place-names are over-whelmingly Anglo-Saxon. In the same paragraph he says 'the Celts left no more than twenty (words in the English language) mostly geographical terms to describe the more hilly and varied landscape' but makes no mention of river names, which are the most obvious examples.
I was particularly interested in his list of words which the Anglo-Saxons borrowed from the Romans before coming to Britain. He gives as examples the words street, pillow, wine, inch, mile, table and chest. and states 'the list of mundane items for which they lacked native terms underlines the poverty of their culture.' But I'm not too sure that the Anglo-Saxons did lack native words for these items. Consider the following:
street Old English road/lane
pillow " bolster
wine " beer/ale (wine is a foreign drink)
inch " finger (finger-breadth can be used as measurement)
mile " furlong (used as measurement)
table " board
chest " This is the hardest to equate. Side board seems to come later and 'fodder' in
the sense of boc-fodder (book case) is a bit obscure. But I find it hard to believe
that the AS never had a word for a wooden box or chest.