Dark Bordered Pearl (Evergestis limbata)
Found more commonly in southern Europe, this is known as a rare migrant to the UK, although there is mounting evidence there may be a small resident population on the south coast in Sussex and/or Hampshire?
It flies between June and September, feeding predominantly on Garlic Mustard and Hedge Mustard.
I also found one in 2021,
"Evergestis limbata" is a species of moth of the family Crambidae first described by Carl Linnaeus in 1767. It is found in Europe. The wingspan is 20–23 mm. The moth flies from June to August depending on the location.