I say 'he' because I can do so with certainty. This is a Muslin Moth and the female is a lovely, pure white. She also shuns the light of traps. Instead she may be seen during the day, scuttling about. Probably shopping.
Only four other moths in the eggboxes last night: two Flame Shoulders, a Swallow Prominent and this newcomer for the year, a Pebble Prominent, named after the two pebbly-looking marks on its neatly-folded forewings. He (or she) is looking thoughtful too.