At least we think this is Caloptilia stigmatella. It is quite hard to tell, for this species has a number of similar relatives. Caloptilia stigmatella is very variable and may be more pregnantly marked. The larvae first mine a leaf. Later they abandon their mines, roll up a leaf and live inside. Experts usually don't search for these tiny species by catching the adult moths, but by studying the mines in leaves. Caloptilia stigmatella is a common species all over the British Isles, on the wing from the end of February to the end of November.