In this sense, see what I was saying too about the Iberian peninsula: despite the optimal environment, in most of the peninsula except for the Greek-influenced (and later Punic-influenced) areas the degree of development was similar to that in Great Britain.There were some levels of organised society many thousands of years before the Romans arrived in Great Britain. Numerous Roman roads (but not all of them, obviously) were built on pre-existing trackways. Megalithic earthworks also tell a tale of organised human society, if not civilisation, on a considerable scale. (I'd highly recommend a visit to Silbury Hill and Avebury to ponder this point.)