In doing a google for another subject, the following site came which may be of interest:

Surname distribution for Isle of Man, Ireland, Cornwall and Scotland (in part) as at about 2002.

It is a fairly new site on quick appraisal with a bit of political content also.

Barry Griffin is the researcherowner and he says his research is not exhaustive and can be added to.

URL: http://baz.perlmonk.org/index.html

Enjoy
Elizabeth