James Pinkerton, Robert Dick Pinkerton and John Wallace Pinkerton MP (seated), uncles of John Wallace McKay.
John Pinkerton (1845 – 4 November 1908) was an Irish Protestant Nationalist politician and Member of Parliament (MP) in the House of Commons of the United Kingdom of Great Britain and Ireland. As a member of the Irish Parliamentary Party he represented Galway Borough from 1886 to 1900.
Born in Ballymoney, Co Antrim, the son of John Pinkerton of Seacon More. He was educated privately. He rose to local prominence as a member of the Ballymoney Debating and Agricultural Societies. He was a tenant farmer, a J.P. of County Antrim, and served as a member of the Coleraine Board of Guardians.
In 1873, he married Isabella, daughter of Robert Pinkerton, of Ballaghmore, Co Antrim.
He was an unsuccessful candidate in the 1885 general election in which he stood as an independent candidate for the North Antrim constituency, where despite defeat, he so impressed the Irish Parliamentary Party that he, a Protestant tenant farmer, was adopted as the party candidate for Galway Borough in the 1886 general election in which he was successful.
During his career as an MP he appears to have been an exceptionally active in advancing the cause of Home Rule and Land reform at Liberal demonstrations throughout Scotland and England.