Foundations of a Saxon church were discovered by dowsing in the 1950s, this being succeeded by a mediaeval church replaced in 1817 with the present building. The fragment of dog-tooth ornament inside the church on the north wall may be the only visible remains of the second church, unless the font is of that date.The significance of the outcome of the Battle of Heavenfield lies in the re-establishment of Celtic Christianity which led to the Golden Age of the Kingdom of Northumbria. The influence of this great movement spread to the Continent and is of special significance in Germany, Eastern France, Switzerland and Northern Italy.
St. Oswald's stands in a churchyard set in the middle of a field, about four hundred yards from the B6318 at National Grid Ref. NY 937696. The field and the churchyard can be entered by gates which should be shut after passing through them. The Churchyard has some excellent trees in it. The gravestones are of various periods, but the most decipherable date from the late 1800s onwards.The church itself has a simple chancel divided at the west end into a vestry, the rest being the body of the church. On the roof there is a simple belfry-arch for the single bell, rung during services. An unusual feature is the sundial on the south wall.The interior is of limewashed stone without any plaster, with a font set near a Roman altar re-used as a cross base at some (possibly mediaeval) date. A fragment of dog-tooth ornament set in the north wall halfway up the church indicates re-use of stone from a church of possibly Norman or Early Mediaeval date.
A wall-mounted lozenge 'hatchment' bearing the coat of arms of the Clarke family, is mounted on the north wall. This recently-restored feature would have been put up at the front of the family house when a death had occurred recently. The motto 'Resurgam' (I shall arise) thus refers to the hope of resurrection as well as to the family itself.The most unusual feature to the 21st century visitor is the gas-lighting with its mantles and glass-shielded burners in the roof, and the candle-holders set in the walls. These and the old American harmonium show that St. Oswald's has never been connected to electricity, mains gas or water supplies, and witness the modest background of this tiny church.
An excellent display on the history of both the church and the battlefield is on screens in the vestry.