Pope Gregory advised Augustine and his fellow missionaries who arrived in Kent in 597 not to destroy idol temples but to convert them to Christian usage. The sites of many cathedrals and parish churches may therefore have been used for religious purposes from pre‐Christian times (see also historic churches). Pagan festivals such as Easter or Midsummer were likewise not suppressed but were taken over by the new religion; see Ronald Hutton, The Pagan Religions of the Ancient British Isles (1991). Features of pagan belief survived alongside Christianity into modern times; see, for instance, James Obelkevich, Religion and Society: South Lindsey, 1825–1875 (1976).
Early Christian writers, notably Bede, make clear the strength of paganism in the Anglo‐Saxon period. This was reinforced in the 9th–11th centuries by Viking settlers in many parts of Britain and Ireland. However, the archaeological evidence for pagan practices is negligible, for heathen sites were focused on trees (especially oak, yew, and ash), stones, and springs. Many pagan sanctuaries appear to have had only local significance. In some cases, place‐names point to their former existence, e.g. at Harrow (‘heathen shrine’; Middlesex), Wednesbury (Staffordshire), and Thundersley (Essex), and the numerous Holywells.
The conversion of heathen sites to Christian usage is sometimes indicated by the choice of patronal saint. For example, St Michael the Archangel, slayer of the dragon in medieval art and protector of high places, was commonly chosen for churches or chapels built on hilltops. Churches and wells dedicated to St Helen may, in some cases, have replaced a heathen site dedicated to the Celtic goddess Elen. The presence of wells in churchyards may indicate a previous holy well; in Wales many chapels were built over a well. Yew trees are a common feature of churchyards; those of enormous girth, as at Darley (Derbyshire), must be ancient. There is room for much speculation here, but little hard evidence; see Robert Bevan‐Jones, The Ancient Yew (2002). The presence of megalithic stones close to churches, most famously at Rudston (Yorkshire), is more convincing proof of continuity with a heathen past. The church at Stanton Drew (Somerset) stands close to a stone circle; that at Avebury (Wiltshire) encroaches on the Bronze Age henge monument. At Breedon‐on‐the‐Hill (Leicestershire) the church stands high above the surrounding plain, inside an Iron Age fort. These examples could be multiplied, but the conversion of such sites took place without any written record. The long timescale of conversion must be emphasized, as must the way this was achieved; kings were converted first, while the ordinary inhabitants of the countryside clung onto many of their old beliefs. See Richard Morris, Churches in the Landscape (1989), ch. 2. See also magic, belief in.