John Cosnahan (1754–1819) was the first High Bailiff of Douglas, Isle of Man, and Deemster.
He was the eldest son of Hugh Cosnahan and Eleanor Finch[1] (1753–1799)[whose are these dates?].
He spoke so powerfully in the House of Lords on 13 June that year that he helped prevent a Bill proposed by the Duke of Athol[3] to pay extra compensation to the Duke for handing the Island over to the Crown.
[1][4] In the last few months of his life he was made a Deemster or stipendiary magistrate, although his appointment was delayed by the opposition of the Duke.
John married his cousin Catherine Finch and they had eight children, a daughter and seven sons, but none of them produced an heir.