The Weather, in Royston

Yet another mystery downpour explained

A mystery downpour for 21 October 2021 is really delayed rain from 20 October 2021.
Removing rubbish from the rain collector released a rush of rainwater.
So 20th and 21st should read 23.4 and 3.4 mm (not 11.4 and 15.4).
The weather station has been given a good wash and brush-up.