Lines drawn between 9,289 (English and Welsh) 1981 census wards on an equal land area map — software by author on an Archimedes computer. Flows are shown when more than 2% of the employed population of an area travel-to-work to the same destination.
On the map we can recognise the familiar city system of England and Wales from just the lines showing the flows of people to work. The barrier of the Humber river is clear. How far some people will travel to reach London shows up clearly.