Clouded Yellow (Colias croceus)
Strikingly orange and black when in flight, Clouded Yellows always settle with closed wings when they show the bright yellow underwing. If you can see the upperwing, the margin is unbroken black in the male and has pale spots on it in the female. In some females the upper-side is a pale whitish grey, though the overall pattern is retained.
A migrant from Europe and North Africa, numbers arriving here vary greatly but in good years they may be present from April until November before embarking on a return migration south
Images L-R: male: female
Flight period: Varies much from year to year but potentially April to November