I get quite a few Double Square Spots in my garden trap each year and wonder if I may have been missing Triple-spotted Clay. I have caught several moths in the last few days that I think may be candidates for Triple-spotted Clay - these are purplish and appear less broad at the base of the wing. As this would be a new record for me I would be pleased if someone could check the attached photos please. I attach two photos I think may be Triple Spotted Clay and one I have as Double Square-spot.
I'm sure you've got it right. Top two Triple-spotted Clays, bottom one Double Square Spot. I've only caught
Double Square-spot in my garden. But, Triple-spotted Clays at various other sites. The main differences as you've noticed, narrower posture, darker appearance and a lighter stripe down the centre of the thorax.