Last weekend I found an occupied mine of this species in a 'green island' on a fallen sallow leaf in a small wood in Llanishen. I've also been seeing plenty of green islands on the fallen oak leaves, though most of these now seem to be vacated which makes the ID more tricky. Most of the occupied ones have been E. subbimmaculella, but I've seen E. heringi too.
Ectoedemia intimella mine on sallow
Ectoedemia intimella larva on sallow
It's probably worth looking out for these green island Ectoedemia on fallen leaves for a bit longer...