The church of St Mary is of dressed and rubble sandstone and comprises a W tower, nave with N aisle, and chancel with N vestry. Little of the 12thc church remains. Repairs were undertaken in the 17thc and the baptismal font is dated 1662, but the church was largely rebuilt in the early 19thc. A chevron voussoir remains built into the exterior of the south wall of the nave and the head of a cross, decorated on one side, is kept inside the church.

The Domesday Survey did not cover this part of England. Cumwhitton was in the Barony of Gilsland, which may have taken its name from Gilbert, son of Buet. In or around 1157, King Henry II gave the barony to Hubert de Vallibus/de Vaux. Thomas de Multon, through marriage to Maud de Vallibus, became overlord of Cumwhitton, part of the manor of Irthington. He died in or before 1271.

His son Thomas de Multon succeeded, but it appears that his mother Maud continued to retain certain powers in Gilsland until her death in the 1290s. In at least one instance Maud is styled ‘D’na de Gilsland et manerio de Cumquinton infra Baroniam illam’. Thomas de Multon (second baron of Gilsland of this name) died in 1293. His son and heir, also called Thomas de Multon, died in 1295, succeeded by his son Thomas Multon, but on the latter’s death in 1313 there was no male offspring. His daughter Margaret thus became his successor. She subsequently married Ranulph de Dacre about 1317, which brought the overlordship of Gilsland into the hands of the Dacre family. In 1333, the Scots ravaged parts of Cumbria, including the lands of the barony of Gilsland, though it is uncertain whether this affected Cumwhitton. The first Dacre lords are not known, however, to have been styled ‘de Gilsland’ until a later Ranulph de Dacre is found referred to as ‘Ranulpho Dacre de Gilleslond chivaler’ in about 1460. By 1485 Humphrey de Dacre had become the chief lord, Cumwhitton still recorded as part of Irthington manor.

In the Papal tax roll of 1291, the church at Cumwhitton is listed under the deaconry of Carlisle, assessed at £8. 14s. 0d, but in 1318 the church was not taxed because of its poverty. The advowson of the church appears as a possession of the priory of Carlisle from at least the middle of the 14thc. Although there is some uncertainty about how this came about, there is an enigmatic reference stating that, during the reign of King John, a member of the De Bavin family had given the advowson to that priory. In the medieval period, Cumwhitton was commonly spelled ‘Cumquintyngton’ and ‘Cumquetinton’.

In 1577, Lord William Howard married Lady Elizabeth Dacre and thus acquired the Barony of Gilsland. Queen Elizabeth I, however, took this land and other areas from him and changed the landholding status. Later in 1601, Lady Dacre bought back the lands and in 1603, William Howard carried out a survey of his barony. Consequentially, Howard seems to have also gained the lease of the church tithes, for in an entry for 1624 in his Household Books there is mention of Thomas Milburn as late curate of Cumwhitton, and in 1628 William Howard paid for repairs to be carried out on that church.

According to Cramp, the first reference to the cross at Cumwhitton was made by Calverly (1899). She has also suggested that this type of cross generally dates to the late pre-Conquest or transitional periods. In 1913, Cox stated that the cross had been originally found in the churchyard wall. Suggestions have been made that the cross was either a churchyard cross or a finial cross set up on one of the gables of the church. The chevron voussoir must certainly date from the 12thc and the cross seems likely to date from the same century.