One of the conspicuous characteristics of the northern dialects of Britain and Ireland is variation in verbal agreement, especially the use of plural verbal -s. Once a mark of a consistent, categorical grammatical system in the traditional dialects of the area, today verbal -s appears in highly complex, hybrid variation patterns in the modern vernaculars. This corpus-based study explores continuities and discontinuities between the dialects involved, and discusses the implications of such hybrid variable sytems for a usage-based theory of grammatical competence.