It is quite possible that my memory has failed me over the 50-odd years aince I read it and it was a book of the time, but I remember it as having a very parochial flavour. The action takes place in southern England but there is no real sense anywhere else in the world exists. When people are trying to escape by sea - to where, exactly? Is conquering England all it takes to conquer the world? Come to that, there is little or no mention of Scotland, Wales, Ireland or even northern England that I recall.