Williams was (and probably still is) the most frequently occurring surname in Cornwall. The last blog looked at an exceptional family with this name. This one reviews the more common Williamses. Williams, like Thomas, Richards, Harris and others, is relatively common in Cornwall (as in Wales) because hereditary surnames were sometimes adopted later, when the norm was to base them on a first name, eventually adding an -s. The surname Williams did NOT come from Wales; the frequency of the surname in Cornwall is the result of a similar process as in Wales.
In the Protestation returns of 1641 we find the name Williams or William in most parishes across Cornwall. But, as the Cornish-speaking communities often adopted hereditary surnames up to 200 years after English-speaking east Cornwall, we should expect to find that the proportions of Williamses were far higher in the west. And they were. The highest incidence was at St Buryan, as far west as you can go. There, almost seven per cent of adult men had the surname William or Williams. In most of Cornwall east of Bodmin it was just one per cent and usually far lower.