[5] As Box was on the pilgrims' route to the shrine of Becket at Canterbury Cathedral, by the end of the 13th century, the church had been rededicated to him.

[5] The tower arches and north arcade are 14th-century, as are the two-storey vestry (which was perhaps a priest's house)[6] and the rib vaulted chapel roof.

[6] In 1831, due to the church being too small to meet demand, the Victorians enlarged it;[5] the Bath architect John Pinch the Younger designed the south aisle.

[5] In 1960, English Heritage granted the Church of St Thomas à Becket Grade I listed status.

[2] Julian Orbach, extending Nikolaus Pevsner's description of the church, calls the north-east Hazelbury Chapel "highly unusual".

Monuments include a large garlanded urn and obelisk to Margaret Blow (died 1755), which Orbach calls "exceedingly charming" and states is attributed to the renowned sculptor Henry Cheere.

[9][10] The 1857 cemetery chapel, rectangular in plan with a north-west needle spire, is described as "unusually elaborate Gothic" by Historic England; it has stonework in contrasting colours and highly carved window tracery.

[13] Today the parish is part of the Lidbrook Group, which also covers St John's church at Colerne.