The Northern Subject Rule (NSR) is a pattern found in Northern British English in which variation between verb endings is conditioned by subject type and, variably, by adjacency to the subject. This study presents the first detailed overview of all the evidence for the NSR in early Middle English, based on new corpus data, and puts it in a diachronic and dialectological perspective. Variationist analysis shows that subject type is a more robust conditioning factor of verb endings than adjacency to the subject; both are more strongly represented in a core Northern English area. These facts are brought together with historical and theoretical evidence to arrive at a formal morphosyntactic analysis and an account of the origin of the phenomenon.

It is shown that the differences in verb endings in the NSR represent a difference between agreement and non-agreement, crucially depending on the differential subject positions available for pronoun subjects and other noun phrase subjects in Older English, which are also found in the Northern early Middle English corpus. This positional difference was arguably an important factor in the rise of the NSR, together with variation in endings which may have been promoted by contact with Old Norse and Brythonic Celtic. Contact with the latter is also a plausible origin for the type-of-subject condition, based on historical and contact-linguistic evidence.

This study is of interest to those working on dialect syntax, historical linguistics and contact linguistics, as well as those working on English syntax and the interface between syntax and (verbal) morphology.