Coleman (1979, 1980a, 1982) has done a great deal to shed light on the population structure and marriage pattern of a modern English city and its environs. Most of the population of England is in urban areas, but almost all the other studies of population structure have been of villages. Coleman analysed the pattern in Reading, Berkshire, and its environs by a study of all the marriage records for a 12-month period in 1972–3, using copies of the registration records in the districts of Reading, Wokingham and Henley-on-Thames. A questionnaire seeking much additional information was circulated to a sample and returns were received from 946 of the 2396 couples married during the specified period. The average couple had been born 103 kilometres from each other – about the same distance as their parents. The average distance from their place of residence when single to the place where they met their future spouses was small, however, compared with the mean distance from the meeting place to the place where the couple resided after marriage. Thus migration after, or at the time of, marriage was an important element in inter-generational migration. As Coleman puts it, the people become individually more heterogeneous but collectively more homogeneous with regard to ancestry (and hence genetic constitution). There is enough migration that in only three generations the population of the built-up area of Reading would be 95% homogeneous.