Confidence: It's likely to be this, but I can't be certain.
Notes: Following from comments on a previous Agonopterix observation, I photographed the underside of this specimen to try and see the line(s) on the cilia on the trailing edge of the hind wing close to the body. I suspect the line is hidden by the body.
It was much to frisky to try and move the forewing with a paintbrush, even after refrigeration.
If I catch another, does anyone have any ideas how I could determine the species without damaging the moth? Try and anaesthetise with ethyl acetate perhaps?