The Celts: an ancient exonym for a modern mind-set?

A deep rift in opinion exists concerning the evolution, if at all, of the Κελτοί/Celtae of prehistoric continental Western Europe into the Celts associated with the modern inhabitants of Ireland, Scotland, Wales, Cornwall and Brittany. On the one hand, the peoples labelled as Κελτοί/Celtae by the Greeks and Romans did not suddenly appear in continental Western Europe in the first millennium BC but had lived and developed there over many generations. Much of what we know of them comes from the Greeks and Romans and from their weapons and ornaments they buried with their dead. Ancient authors never assigned the label Κελτοί/Celtae to the inhabitants of the British Isles On the other hand, over twelve hundred years later, Lhuyd published his work in the field of comparative linguistics in 1707AD identifying similarities in the languages of his day in Brittany, Cornwall, Ireland, Scotland and Wales with that of ancient Gaul, choosing the label Celtic for this group of languages. Other eighteenth century scholars concerned with early Europe and with a growing knowledge of prehistoric monuments and artefacts then created their vision of the past peopled with Celts and Druids. This exposition examines relevant classical and present day texts concerning history, language and linguistics, literature, archaeology and genetics sources outlining essential arguments particular to both perspectives, collating interdisciplinary arguments where possible whilst demonstrating inherent and perhaps irreconcilable incongruities. A final discussion deliberates on possible time-line tracks or interconnections between the ancient Κελτοί/Celtae and the present day Celts