Off the top of my head, I dont know, but it seems (judging from th 1881 and 1998 census, available at http://www.nationaltrustnames.org.uk/Surnames.aspx ) that Mathews is a a predominantly welsh/cornish. However, if Mathews is a contraction of Mathewson, then that'd be a lowland scottish name.

Dont know if that helps or not, eventualy, you'll reach a dead end, I cant track my family back any further then when they left Ireland, because ireland was a 3rd world country at the time and didnt have very good records of its populace. Internet reasearch leads me mainly to MacFarlane or MacNeil, but gives me nothing for certain (mainly because the family spent less then a generation in scotland before moving to Tyneside).