This is a Brimstone butterfly which I caught and pinned many years ago when I used to be a collector. When arranging a collection it was always important to attach a label to the pin noting the date and place of capture, otherwise the specimen is of little scientific value
The Brimstone is perhaps the greatest and best known signifier of Spring in Britain (it hibernates in the ivy to emerge on the first warm days) and is almost impossible to approach, let alone catch or photograph
This is a female, the male being an even richer and darker yellow colour