Theory that \'Celts\' are a myth

[D B Campbell]

... the Celts are a myth and that the term was invented a few centuries ago to perpetuate the cherished myths of dark age Britain.

I presume that this is simply a misunderstanding of the long-running debate (typified by Simon James' The Atlantic Celts, but instigated earlier -- afaik -- by John Collis) which questions whether we can legitimately talk about "The Celts" as the indigenous peoples of western Europe, or whether there were really fundamental differences separating the different peoples.