Thank you all for the ideas. I will look into Cyara variants. The family were English with no known ties to Ireland but it's worth a further look.
Chempat, I'm descended from Henry Slater's sister, so he's not my direct line of ancestry. Until recently it seemed Henry had vanished off the face of the earth as I could find him in no UK census, but just found a document related to probate in 1847 regarding the will of his grandfather, which helpfully recorded him as a brewer of Rochester, Monroe Co., New York. So I know this is the right Henry but no luck tracing any of the family further so far.
I do wonder if they could have gone to Canada since Rochester is so close the border.
Thanks
Alexander