There are more hominoids alive than have ever been born. When messolithic hunters clashed with neolithic settlers the numbers were biblical almost camp and theatrical as soldiers enclosed their own and conquered tribes in walled cities. They were to care for these like fondly regarded cattle. Leaders and captors regarded their charges as little more than animals. This syndrome exists fiercly now and today but subterrannean and very deep in the psyche of modern neolithic hominoids. In colder climes strangers wandering in to defended territory would end up in a bog or hillside ditch with some sort of fatal cranial damage. Refer to film by Nils Gaup Pathfinder about a boy who leads a Norwegian tribe to safety. This was all to be expected and lasted longest in Europe in Corsica, Donegal and Jarrow right up till only 150 years ago. Tribal insticts acted out by warring youths, teenagers and young adults. Societies with young populations are in a constant state of war replinished in the minus and kept young by the attrition of killing. The tribal elders would be in Maiden Castle wondering when death would come.
Much of England which was submerged in Roman times would be submerged again and Nottingham County Council logo becomes a tropical tree not an English Oak. Newark-on-sea becomes the capital of north Nottinghamshire and Cuckmere Haven is left to the sea.
However it is oil consumption which eventually causes shortages of food and the English perish last of all by vitue of having plenty of water and rainfall.
Food production from the great escarpment along a line east of Letchworth to Ashby de la Zouch gets redirected to the home market and the the last supper is quaffeddown with Suffolk Strong Ale and Stilton Cheese made in Cropwell Bishop.