1264-1800: A Topographical Dictionary of Ireland by Samuel Lewis discusses the administrative history of Antrim. It is uncertain when Antrim was made a County and given representation as such in Parliament. Something like the modern arrangements seems to have originated in 1584 when the Lord Deputy Sir John Perrot divided the area into baronies. From whatever point the county constituency existed it comprised the whole of County Antrim, excluding the parts in the borough constituencies of Antrim (from 1666), Belfast (1613), Carrickfergus (1326), Lisburn (1661) and Randalstown (1683).
^The Lord Lieutenant wrote to the Sheriff of Antrim on 2 November 1665 recommending Poyntz as the successor of Skeffington, who had inherited a peerage in September as Viscount Massereene. In the absence of evidence to the contrary it is assumed that, in this period, such a recommendation was tantamount to election.
Bergin, John (2009). "Upton, Arthur". In Kinsella, Eoin; Clavin, Terry; Evers, Liz; Gallagher, Niav; Maume, Patrick; O'Riordan, Turlough (eds.). Dictionary of Irish Biography. Royal Irish Academy; Cambridge University Press. doi:10.3318/dib.008767.v1. Retrieved 2 November 2022.
O'Hart, John (2007). The Irish and Anglo-Irish Landed Gentry: When Cromwell came to Ireland. Vol. II. Heritage Books. ISBN978-0-7884-1927-0.
Leigh Rayment's historical List of Members of the Irish House of Commons. Cites: Johnston-Liik, Edith Mary (2002). The History of the Irish Parliament 1692-1800 (6 volumes). Ulster Historical Foundation.