Confidence: I'm as sure as I can be.
Notes: A 4mm adult leafminer. Appears to be a Phyllonorycter species but there are many and they look similar to each other after having looked through them in UKmoths. This was found resting on a willow leaf but there is a a lot of hazel at the site and a mature sparse plantation of sitka spruce all around it also. Mature beech close by too. Any help bringing it to species would be much appreciated.