Mildenhall was granted to Glastonbury Abbey in the 8th century, and a church may have been built in the early 9th century. The base of the tower of the present church is from the 9th or 10th century, and the rest is the result of stages of rebuilding in the late 12th century and early 13th. In the 15th century the third stage of the tower and the clerestory were added, and most of the windows renewed. The plaster ceiling of the chancel is early 17th century, and the earlier nave roof was embellished at the same time. In the 18th or 19th centuries the south aisle was partly rebuilt and the south porch added. In 1816 a round-headed window was added to the south side of the clerestory, and another over the west door. The church is notable for its oak fittings, installed in 1814–1816 and called "outstanding" by Historic England. Julian Orbach, updating Pevsner's work, writes "in Gothick style, the very model of Late Georgian arrangements ... Unusually for rural England everything matches and is to a very high standard". Components include box pews, children's benches, twin pulpits (one a reading desk) with tall backs and decorated testers, and the stone font with wooden cover; and in the chancel, ornate pews, panelling and the reredos with its painted texts. Other work included stone flooring in black and white, and new oak doors. The west gallery, with curved panelled front to accommodate the organ, was completed in 1821. The refitting cost altogether around £2,000 and was instigated by Charles Francis (rector from 1788 until his death in 1821, also rural dean) and paid for by himself and twelve local property-owners, named on six shields displayed in the church. In the heads of the chancel windows are fragments of 15th-century stained glass. The north-west window depicting the Raising of Lazarus, 1882, is by Mayer & Co. of Munich. There are six bells, five of them cast in 1801 after melting down the four that had been installed in 1596. The church has several marble memorials, including two by Joseph Harris of Bath for Thomas Baskerville (1818) and Rev. Charles Francis (1821). In 1966 the church was designated as Grade I listed. Sir John Betjeman refers to St. John's as "a church of a Jane Austen novel". Simon Jenkins includes it in his England's Thousand Best Churches. St. John's parish is