The larva of the Cistus Forester feed exclusively on Rock Rose, which is not a flower which is found on the gritstone moors whereas the Forester feeds on Common and Sheep's Sorrel which is much more widespread on both limestone and acidic grasslands. They are usually separated in the field on size, the Cistus Forester is a generally couple of mm smaller than Forester. I think given the habitat that The Forester is the more likely identification but either is a very interesting local record
I checked the area today without success in intermittent sunshine.
|Forester or Cistus Forester Moth (c. Ken Smith)|