This butterfly belongs to a cryptic species complex which consists of tree butterflies: L. reali (occurs in Spain, Italy and south of France), L. juvernica (occurs in Ireland, and from west France to east of Kazakhstan) and the L. sinapis (found in most of Europe and Caucasus and in areas of Asia and more).

So this could be the L. juvernica as well.

Read more about the Cryptic species complex here: PDF File

Note: Page 6, Figure 5 has e very nice Phylogenetic relationships map with a proposed speciation scenario.