This Presbyterian family were located in the Fethard area of county Tipperary from at least the mid 17th century. In 1703 Mathew Jacob bought the lands of Johnstown, 370 acres in the barony of Middlethird, part of the estate of James II, for £900. Mathew Jacob of St Johnstown married Elizabeth Minchin of Shangarry. Their three sons settled at Ballingarry (Samuel), Mobarnan (Mathew) and Coolmore (John). In the mid 1770s Mathew Jacob of Mobarnan's estate was estimated to be worth £6,000 (Kilboy Papers). In 1782 Anna, daughter and heir of Mathew Jacob of St Johnstown, county Tipperary, married Richard Pennefather of New Park. In the mid 19th century Matthew Jacob held land in the parishes of Ballingarry and Killenaule, barony of Slievardagh and Donaghmore, Magowry and Peppardstown, barony of Middlethird, county Tipperary. At the same time Samuel Jacob held land in the parish of Magorban and Robert Jacob in the parish of Cooleagh, barony of Middlethird. An estate of 2,865 acres in the baronies of Middlethird, Slieveardagh and Kilmanagh, belonging to Samuel and Robert Jacob, both "of Mobarnane", was advertised for sale in April 1851. The sale included Mortlestown Castle. This estate, plus an additional 800+ acres including Mobarnane, was advertised for sale again in December 1851. The Tennants bought Mobarnane and most of the Jacob estate. The Freeman's Journal reported that a Reverend Thomas also purchased some lots.