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The village takes its name from a technically confused reference (a friary is generally a house of Franciscans and in any case not of Carthusians) to the Witham Charterhouse, a Carthusian Priory founded in 1182 by Henry II, which had peripheral settlements including one at Charterhouse and possibly another at Green Ore. It is reputed to be the first Carthusian house in England. One of only nine Carthusian Houses in the country, the priory did not survive the Dissolution of the Monasteries. At the Dissolution it was worth £227; the equivalent of £52,000 today (2006). Excavations in 1921 revealed buttressed wall foundations and building rubble including glazed roof and floor tiles. It is a scheduled ancient monument.
Part of the priory now serves as St Mary’s Parish Church. Although the original building dates from around 1200 it was altered in a transitional style in 1828, and then rebuilt and extended 1875 by William White in “Muscular Gothic” style. It has a three-bay nave and continuous one bay apsidal chancel, built of local limestone rubble, supported on each side by four massive flying buttresses. The plastered interior is entered through a Norman style doorway. Inside the church is a scraped octagonal font dating from around 1450. The Jacobean pulpit contains medieval work and there is a royal arms of 1660 at the west end. The stained glass windows contain fragments of medieval glass, with the windows in the south being made by Sir Ninian Comper. It has been designated by English Heritage as a Grade I listed building.
The former Village Reading Rooms are in a thirteenth-century building which was once a dovecote associated with the Priory. They are grade II* listed building but are included on Mendip District Council Historic Buildings at Risk Register.
The village has older roots. A wealth of nearby tumuli is indicative of ancient human settlement. An archaeological dig in 1985 discovered a neolithic axe and a Roman road. The village is mentioned in the Domesday Book of 1086, when it supported 11 villagers.
The former railway station at Witham was the end of a branch line through Shepton Mallet, Wells and Cheddar. The station closed in 1963 although the main line to Exeter remains open. The nearest railway station is Bruton. Part of the redundant line that ran to Shepton Mallet now forms the East Somerset Railway.