I heard a poem from an old man with a long memory at Stradbally, Co. Laois, Ireland, in the 1970s- I can remember but one verse that runs as follows:

'A ploughman poor his grandsire was,
His mother was a Trench-
Supported by the Warburtons
That lived at Garryhinch.'

I also remember the mention of that the poem contained some form of a 'curse' 'upon you, John Adair.'

The implication of the first line was that Adair was descended from   an 'assignation' between two persons of very different classes, and that, despite his humble origins, Adair proved most fitting for the role of a   cruel and tyrant landlord.

I cannot vouch for the truth of the implication but, just let's say that Adair must have earned the execration that has been committed to verse- and that has endured in that medium.