A typical blotch in close-up and...
...a larvae extracted from its leaf
Lightly affected leaves on the first of July
Heavy infestation on mid july
A heavily infested tree
A few specks on leaves of a lightly infested tree.
There is currently a survey on to follow the moth spread across the UK and monitor the levels of infestation and the level of natural control by parasitoids. It is very easy to enter data about your local conker trees and the website is here.