Pearly Underwing - the light 'biscuit' variant and one of two trapped last night. Compare with the dark one below - Ed - didn't check underwing of this one and not certain id is correct. Does wing shape suggest Turnip Moth?
I can see the beauty in most moth species but this species is about as plain and uninteresting as they come. The lack of distinct oval and kidney markings is in itself an id feature, as is the pronounced grey-dusted 'mohican'. Confusion species include Turnip Moth and Dark Sword-grass (see bottom photos) but I almost overlooked the darker of the two as a Large Yellow Underwing. Pearly Underwing is an immigrant species but this is the first time I've recorded it in Britain, so it's a welcome addition to the garden list. It's not especially rare but it seems pretty tied to coastal migration hotspots like Portland. I'm really hoping for Radford's Flame Shoulder but I'd settle for a White Speck - probably the commonest immigrant species I still need. Otherwise last night's numbers were very low with just one Silver Y and a couple each of Rush Veneer, Rusty-dot Pearl and Diamond-back.
I was happy this was Pearly Underwing but nevertheless I was glad it let me gently shift the forewing to reveal the translucent underwing complete with black veins and pinkish-pearly sheen, from where the species obviously gets it's name.
Above - Dark Sword-grass and below Turnip Moth - two potential confusion species.