It isn't just confined to young saplings but old Beech are badly affected as well. It could be the result of the Beech Leaf Miner--Orchestes fagi. I can't say I have noticed this much damage to the leaves in previous years.
Less Chlorophyll will mean less photosynthesis and progressively weaken the tree. In combination with this lengthy dry spell and Beech having a shallow root system, it is not looking good.
Is this type of leaf damage noticeable throughout the valley or is it just Todmorden? Can anyone confirm this weevil is the culprit?