My recollection is a post a while back estimated the British Isles have been the subject of a least half a dozen attempts by man or our predecessors to colonize them, who have been driven back each time - until now. The results of this attempt remain to be seen, in the next glacial.
:’) The Sinking Lands, which lay west of the current coast of Britain, and including (generally speaking) the better-known Lyonesse, survived in British legend into the Middle Ages (and thereafter, as written versions); at least one similar survival into modern times concerns stuff submerged in what is now The Wash. Evidence of their former existence as dry land takes the form of submerged, broken-off forests (rooted stumps), the odd stone artifact, etc.