This is a fun and fascinating read but it does seem the Celts can do no wrong as far as Peter Berrisford Ellis is concerned! His partisan approach makes you wonder if what you're reading can really be relied on.
There are times when the author gets his facts wrong, too. The idea of the savage Anglo-Saxons driving out or wiping out the Celtic indigenous population of Britain has been shown to be false by modern DNA evidence. In fact, even the English today have predominantly pre-Roman genes, showing that the invading Anglo-Saxon and Viking minorities settled and interbred with the locals rather than simply slaughtering them all. No doubt the Anglo-Saxon invasions were a brutal affair, but the idea that England underwent some kind of ethnic cleansing has been disproven. It's none too impressive that Ellis represents this old myth as an indisputable fact!
He also claims there are only 18 million Celts left in Europe. Considering they once stretched right across Europe, that is very hard to accept. By what mechanism could ancient cultures have utterly annihilated such a vast population? Is it not more likely that the Celts' descendants still exist all over Europe?
Admittedly, Ellis does decide to define 'Celt' mainly as someone who speaks a Celtic language. Indeed, he uses this argument to dismiss any debate over whether the Celts were really the single ethno-cultural group that we imagine. But at the end of the book he completely contradicts his own definition by claiming there are 18 million Celts left, only 2.5 million of whom speak Celtic languages.
Well, if we define Celt as a speaker of a Celtic language, there are only 2.5 million left! If we define them as people with ancestors who spoke Celtic langauges there are probably hundreds of millions left, scattered all over the world. But the 18 million figure has no foundation at all, no matter whose definition you use!
Of course, the idea of the total 'ethnic cleansing' of this supposedly close-knit cultural group by the evil Romans and Anglo-Saxons is a popular romantic idea. But in truth, it is far more likely that certain early Celtic tribes imposed their language and culture on other non-Celtic tribes, and in turn had their language and culture subsumed into other more dominant groups. No doubt this would have been accompanied by a lot of bloodshed in both cases. But DNA evidence does not support the idea of 'ethnic cleansing' at all. It may not be such a romantic story, but it's much more uplifting, and probably more true!