I just received a review copy of Saxons, Vikings and Celts: The Genetic Roots of Britain and Ireland. I won’t be talking about it until January as I’ve agreed to hold it until it starts being marketed after it’s published here in the states. But, I do think it is kosher if I report the data which Bryan Sykes repeats from the 19th century work The Races of Britain.
1) Blonde hair is most common in East Anglia and Lincolnshire, with high values in Yorkshire, Cumbria, the north of Scotland and the Hebrides. It is least common in Ireland and Cornwall. Intermediate values can be found in most of England and Wales.
2) When it comes to eye color the cline is different. Brown eyes are common in the south and the east, where they exceed 40% in East Anglia and Cornwall. In Ireland, Yorkshire and Cumbria the frequency of blue or grey eyes rises to 75%.
If you want a genetic moral from all this it is that eye color and hair color are not closely linked. There does seem to be some correlation between areas with a high frequency of red hair and light eyes (e.g., Scotland), but that is likely because the former trait is derived from a serial loss off function for melanin production on several loci, and light eyes are a natural byproduct of this genetic architecture. There are implied modal combinations, such as many dark eyed blondes in East Anglia, and the dominance of dark haired but blue eyed folk in Ireland, and the dark eyed and dark haired Cornish. Since I have British readers I will leave it to them to judge the accuracy of these ascertainments, though keep in mind that the data was collected in the late 1800s, so population movement might have homogenized the distribution of traits a bit.