I can't recall ever seeing this moth in Co. Durham (but I probably haven't looked in the right places) until last year when I was surprised to see a couple flying in fields between Blaid's wood and Low Burnhall Woodland Trust reserve, on the outskirts of Durham city. Then yesterday, in the same spot, we found numerous (gave up counting after 100) well-fed larvae on ragwort. Many were ready to pupate and were crawling away from the defoliated food plants.
I wonder how this coastal insect came to be established in this inland location? Maybe someone has deliberately introduced it, because there has been quite a lot of research (although mostly in the US) on using this insect as a biological control agent for ragwort, which is highly invasive and poisonous to livestock.
It will be interesting to see how well the population persists, but it must have come through last winter's freezing conditions, which are likely to have been worse here than at coastal locations, without a problem.