But this is South Essex, as I understand it the driest part of the country.
Isn't the ground pretty bone dry for most of the time in spring/summer,
anyway?

As Keith says below it is a low rainfall area generally, although I am
closer in towards London. It's usually the intensity that peters out as
systems come in from the SW, but this splitting and completely missing out
seems to be more common of late and different to the classic reason for
below average rainfall. If you run the radar from 16.30 to 19.30 it really
is quite odd.

Dave