This video from the Netherlands says about itself (translated):
Warden Erik van der Spek reports that last Saturday, for the first time ever a scarce tortoiseshell butterfly was seen on Texel island: in De Geul nature reserve. Last year, this species invaded the Netherlands for the first time, but had not been seen on Texel then.
Butterflies are full of surprises and this year they have saved their biggest until last: in the midst of an awful November, subtropical butterflies have been spotted on England’s south coast. The remarkable appearance of the long-tailed blue, a butterfly happiest in the heat of Africa or Australia, raises a mystery: will these insects simply die this winter? Here. Update: here.