I may be unscholarly and simplistic, but I am not political. The trouble with Wikipedia is that you never know if the writers speak with any authority. Don't believe everything you read on websites. I prefer books and the following extracts may be found in "Britain BC" by Dr Francis Pryor MBE MA PhD FSA MIFA

Page 118
"Some of us had been taught at university that the Celts invaded Britain at various times in the Iron Age. The trouble was, our digs showed that these so-called invaders lived in the same villages and sometimes in the same buildings as the people they were meant to have replaced. Then Professor Roy Hodson of the Institute of Archaeology in London published two papers in 1962 and 1964, which effectively demolished the various Iron Age invasions. More recently, Simon James has cogently argued that the Celts themselves probably never existed as a distinct cultural entity. Not surprisingly, this has not proved particularly popular in Irish academic circles."

Page 343
"We've already seen that the archaeological record can provide no convincing evidence for mass migrations into Britain prior to the Roman Conquest. Simon James has debunked the Celts and Professor Roy Hodson effectively destroyed the numerous Iron Age "invasions" from the continent"

Page 380
"We now know, moreover, that there was no such thing as a Celtic "invasion" of Britain or Ireland"

Note the dates of Hodson's papers - 1962 and 1964. If you still believe in Celts you are more than 40 years out of date!