Christianity was declared the official religion of the Roman Empire during the reign of the Constantine (AD 324-37). From about 330, large churches began appearing in the western provinces, but evidence of church buildings in Britain is scarce. Christian symbols found on decorative objects, on wall paintings and in mosaics from the late 4th century suggest that Christianity appealed to some educated and wealthy Romano-Britons.

The most striking evidence for the spread of Christianity in south-west England comes from an excavation at Poundbury in Dorset, where many of the inhabitants of Durnovaria (Dorchester) were buried. About a thousand graves contained wooden coffins, oriented east-west in the Christian manner. One coffin held a coin of the emperor Magnentius (reigned 350-3) with the chi-rho monogram (the Greek form of the first two letters of Christ’s name) on the reverse.

A workshop of mosaicists seems to have been established in Dorchester at the end of the 4th century, which was responsible for mosaics in villas at Frampton and Hinton St Mary. The designs are based on traditional pagan imagery but incorporate Christian symbols. The portrait of Christ on the Hinton St Mary pavement, the first known representation of Christ in Britain, links the province with the wider world of the Western Empire.