Irish Measure was one of three systems which were used in different areas, but who were the ancestors of the third measure most made up of?
Irish measure:  A third system, "Scotch measure" or "Cunningham measure", was also used in Ulster Scots areas. Ulster Scots people:  Their ancestors were mostly Protestant Lowland Scottish migrants, the largest numbers coming from Galloway, Lanarkshire, Renfrewshire, Ayrshire and the Scottish Borders, with others coming from further north in the Scottish Lowlands and, to a much lesser extent, from the Highlands.
Protestant Lowland Scottish migrants