Since the time of the Norman Conquest Llanilid and neighbouring Llanharan were part of the Welsh lordship of Ruthin, one of the lordships of Glamorgan in the cantref of Penychen.[2][3][4] The region was wild and heavily wooded, consisting of scattered hamlets in the clearings and the land was predominantly taken to pastoralism.[2] Tradition states that Rhys ap Jestyn was granted lordship of the region by the Normans, but there is little historical proof of this. It is known that the Normans left the region fairly untouched, though the motte in Llanilid, believed to be Norman in construct, show evidence of encroachment into the area.[2] Eventually the lordship of Ruthin was partitioned, and by 1245 Richard Seward of the neighbouring lordship of Talyfan had wrested the region of Ruthin away from its Welsh rulers.[5] In 1245 Ruthin, along with Talyfan and Llanblethian, were confiscated by Richard de Clare.[6]
Little is known of the early history of Llanilid after the end of Norman control, though it is known the region boasted an ancient church, a smithy and several displaced small holdings. Most of the farms dealt with livestock, with only the western area of Llanilid, in modern times known as Felindre, possessing fertile land.[7] This portion of Llanilid was given over to the Knights of St. John before 1338 and was known as the manor of Milton. The manor of Milton was the chief possession of the Knight of St. John within Glamorgan and its primary form of income for the order was a water mill which sat on the banks of the River Ewenny.[2][7] This demesne and the mill was let and its oversight entrusted to a separate seneschal.[8] When the order was dissolved in 1540, Milton was purchased by John Thomas Bassett of Bonvilston.[8] Around this time, Llanilid had a population of around a hundred people whose land was controlled by absentee landlords. By 1666 three land owners, Humphrey Wyndham of Dunraven, Sir Robert Thomas of Llanmihangel and David Jenkins of Hensol, owned most of the parish.[9]
Llanilid remained a rural parish throughout the 18th and 19th century, though with the coming of the industrialisation of South Wales its northern border was transformed by a large opencast mine. In 1848 Sophia Crichton-Stuart, Marchioness of Bute, wrote to her land agent, expressing concern at the actions of the Earl of Cottenham, then Lord Chancellor, who had the patronage of the parish, "where hardly anyone speaks.