The church at West Grimstead is dedicated to St. John, although whether to the Evangelist or the Baptist is not known. It is thought to date from the 11th century with local tradition giving a date of 1087-1100 but the style visible today is 13th century, as can be seen in the arches of the arcades. However it is possible that the north and south aisles were additions to a late 11th or 12th century church with just a chancel and nave. Features such as the font are certainly Norman. The early doorway was in the west wall of the nave, filled in when the tower was built in the early 18th century, while there is another blocked door in the north wall in which a somewhat inappropriate window has been inserted. There is another blocked doorway, with similar window, in the south wall opposite the north doorway, which is to be expected in a church of this period; the southern one could have been the entrance for the manorial family. The present entrance is through the west wall of the tower. The whole appearance of the church is a little unusual. The early walls are of rubble stone and flint with random blocks of dressed stone and ashlar quoins, windows and doorways. A little brick has been used in patching and the roofs that swoop to the ground are of old tiles. These could well have been thatched until the early 18th century.
The whole church has the appearance of having served a small community that did not have a great deal of money but which managed to maintain its church without drastic alteration.
Inside the church is an Early English piscina, a grotesque carved head high up on the inner vestry wall; this is similar to ones found on the cathedral site at Old Sarum and may have come from there. The oak altar table could be 16th century while the oak pulpit is likely to be Jacobean. The hatchment on the west wall of the nave baers the arms of Queen Anne.
The major alteration came at the beginning of the 18th century when the brick tower was built. It is two or three centuries too late for the competitive tower building that took place between neighbouring villages but at that time the churchwardens, rector or a local landowner obviously decided that their church should have a tower. It is quite a surprise as it is built in brick but the reason for this could lie in the owners of the manor. Richard Compton sold the manor to Sir Stephen Fox, the Earl of Ilchester and brick buildings feature in the families of both men. The Comptons built and owned Compton Wynyates, a perfect Tudor brick manor house while Sir Stephen was the son of Stephen Fox, who built the brick church at Farley in south east Wiltshire.
Much renovation was carried out by the Rev. E.B. Martin, who was rector from 1864 to 1901. In 1866 commissioned an architect’s report, removed the ‘lime-white’ from the interior stonework and raides the floor by 12 inches in an attempt to cure the rising damp. The chancel was restored, pews replaced and many other repairs undertaken. Lord Radnor, then the lord of the manor, paid for the whole roof to be repaired.
The earliest recorded rector at the church was Ricardus Brionne in 1294. In 1858, The Rectory was built next to the school, replacing an Elizabethan parsonage and this became a private house in 1948.
In 1923 there was restorative work done on the church roof which included the removal and replacement of damaged tiles and the replacement of old wooden beams by new oak ones. Ivy was removed from the church during this process as it was thought to be the culprit of much of the damage. In the 1930s damage to the north aisle and cracks by the window in the north wall were found and repair costs amounted to £48. A larger roof repair bill in 1986 amounted to £10,000.
A harmonium was installed in the church in 1880 by the rector and his relations at a cost of 35 guineas and in 1922 it was replaced by an organ which had once been used at the Royal Albert Hall. The churchyard was extended in 1913 after land was donated by the Earl of Radnor. In 2012 the church was under repair and the churchyard grass was kept mown by sheep. The parish registers from 1717, other than those in current use are held at the Wiltshire & Swindon History Centre in Chippenham.