The son of Averell Shillington (1802-1897), of a prominent Methodist family of Portadown, County Armagh, by his wife Mary (d. 1838), daughter of James Whealy,[1][2] Shillington ran the Castleisland Linen Company for many years, and in 1897 inherited the business from his father.
[3] Shillington first came to prominence as the chairman of the Irish Land Committee on its formation in 1883, an organisation aiming to draw together numerous local tenant's rights bodies.
[4] The following year, he became the first president of the Irish Protestant Home Rule Association, a body of Liberals aiming to show that a significant number of Protestants in Northern Ireland supported Home Rule.
[5] At the 1895 general election, Shillington stood in South Tyrone as an independent nationalist, narrowly losing to the Liberal Unionist Thomas Wallace Russell.
[8] These appointments entitled him to the style The Right Honourable By his wife, his first cousin, Sarah, daughter of Thomas Averell Shillington (1800-1874), of Tavanagh House, Portadown,[9] he had issue including a son, Thomas Averell Shillington, who took over the Castleisland Linen Company until its liquidation in 1929.