Dark-haired, dark-eyed British women, Spanish genes?
I cannot independantly verify this. I have but the theory of a British person I talked with many years ago.
The presence of dark-haired and dark-eyed British women, for example, Jaime Murry, Gemma Arterton, Kate Beckinsdale, may be due to the addition of Spaniard genes into the British gene pool.
Spain was a world superpower in the mid-15th century, and possibly for a short time, as powerful as a hyperpower. Contemporary Portugal would have qualified as a minor superpower while contemporary England would have been just a great power along with France. So much for the history lesson, but Spanish diplomats, noblemen, merchants, and sailors would have all visited England for commerce and trade throughout all that time. Men being men the world over, Spaniard men living in England even for a short time would do what comes natural to men. Hence, the original population of Celtic red-heads and light brunettes and blonde, blue-eyed Anglo-Saxons would have soon include dark hair and dark eyes. Within a very short time, beautiful, fair-complexioned, dark-haired and dark-eyed English and Welsh women would grace the lands of Britain.