For some obscure reason the most visited page on this website has consistently been 18th century surnames by parish. To accompany this I’ve spent the Christmas period compiling a list of surnames for each parish in the mid-17th century and this can now be consulted here.
In 1642 across Cornwall over half of men (57%) shared the 10% most common surnames. Those most frequently occurring at this time were:
The smaller the area the less concentrated would be the surnames. Thus, in most parishes in Cornwall, somewhere between 20% and 30% of men possessed the 10% most frequently occurring surnames in those parishes. The smallest proportions were found at Blisland and at Ruan Major, with 17%. Meanwhile, the map below shows those parishes where the ratio exceeded a third, with more than 33% of men being accounted for by the top 10% of surnames.
This hints that in the 1600s surnames were more concentrated in the east of Cornwall, where they had been hereditary for the longest period, and in more marginal parishes in the west. It may also indicate a relative lack of migration in and out of those parishes.