‘[T]hunder storms is verry dangese in this countrey they come in less than a minnits notice...’

It has been suggested that use of the Northern Subject Rule (NSR) in Southern Irish English (SIrE) is the result of diffusion from Ulster-Scots dialects of the North of Ireland, where many Scots settled in the 17th century. 19th-century Irish-Australian emigrant letters show the main NSR constraint — which permits plural verbal -s with noun phrase subjects but prohibits it with an adjacent third plural pronoun — to have been as robust in varieties of SIrE as it was in Northern Irish English (NIrE) of the same period. Before British colonisation of Ireland, the NSR was present in dialects of Northern England and the North Midlands, regions which contributed substantially to English settlement in the South of Ireland. It is therefore suggested here that the NSR in SIrE might be a retention of a vernacular feature of NSR dialects that were taken to Ireland from the English North and North Midlands rather than a feature that diffused southwards in Ireland after 1600.