My results were 41% British Isles, 48% Scandinavian and 11% Southern European. My genealogical ancestry is all British Isles.
For Scandinavian think of the Viking incursions and settlements along all the northern and eastern coastlines of the British Isles. For Southern European think Roman conquests.
Your DNA Ancestry is a lot older than your genealogical ancestry. Ancestry itself has a good explanation of these results on the page where it shows your Genetic Ethnicity. Remember, this is your Genetic Ancestry, not your Genealogical Ancestry and it can be quite different to what you have always assumed.
I was surprised at first but after reading some history of the various movements of peoples around Europe I'm not terribly surprised.