The geography of this seems to relate to wealth and social class. Perhaps the poor cannot afford to isolate and survive on less than £100 per week. Especially in the poorer parts of northern cities. Why is the same not true of London, which has large areas of deprivation, and wider exposure via public transport than most.
The next month will be telling as schools, and particularly universities return, PS. social distancing for secondary students seems to be being ignored around here, with lots of hugging and large groups in social areas!
Figure for North Somerset has jumped from 2 per 100.000 to 14 in last 2 weeks. I am still not sure what this means in terms of risk (of serious illness or death!).