I'm tracing Shankland ancestry in Scotland and Ireland, and there seems to have been a constant migration between north Ireland and south-west Scotland, so that it's difficult to work out who's Irish and who's Scottish - the term Scots-Irish comes in handy here. I think the families were originally Scottish, but whereas in Scotland they use the name Shankland, in Ireland it becomes Shanklin. DNA indicates that the two names are quite closely related.