Why does the north east corner suffer from a lack of customers yet the NW,
SW and SE do fine for numbers? Any ideas? Could it mean the lack of
passenger numbers further closes in the North East corner?

I suspect this refers only to the loop of the Central Line via Chigwell. It
goes through some moderately populated areas but I suspect multiple car
ownership around Chigwell is high. The low use of the tube is probably
caused by years of low service frequency, having to change trains to reach
central London and early close-downs putting people off. It will take some
time to change attitudes to public transport.

The District Line is incredibly busy until East Ham and remains reasonably
busy until Dagenham/Elm Park.