Optional OV order in Later Middle English (LME) has given rise to conflicting theoretical accounts. Earlier analyses postulating movement to AgrOP or alternative base orders are found to be inadequate to deal with the occurrence of OV in non-literary LME; in a large database of 15th century private familial correspondence, residual OV order is found to have been productive only with negated objects. Multiple subject constructions with there expletives showed the same restriction. These phenomena are accounted for by postulating overt Neg Movement (Haegeman 1995) as a permitted option in LME. In this framework, it is argued that LME showed a mixed typology having both Neg movement and a null Neg operator. LME had three ways of satisfying the NEG Criterion (Haegeman 1995): Merge not in Spec NegP, coindex [OP]i … [XP(Neg)]i, and Move XP(Neg) to Spec NegP. Modern English has only the first two. The distribution in this period of negative concord with not is shown to support our analysis.