The Church of St Michael was built in the 12th century. It is a grade I listed building
William of Normandy gave Duns' manor to Walter de Longueville (near Dieppe) plus some others for services rendered during the Battle of Hastings. His nickname was Giffard, from the Norman/French word "giffles" meaning "fat cheeks", By the time of the Domesday Book, 1086, he had given Brimpsfield to his son Osbern.
The Giffards had a very independent spirit and were rogues. In spite of this they were pious in their own way and built the stone church, dedicated to St Michael, outside the castle moat in the old Saxon churchyard. To the North side there was a priory or cell given, with the church, by a Giffard Baron in the early part of the 12th century to the Benedictines of Fonteray in Normandy. In the 14th century the piscina in the church and the porch with the stone benches were added probably by John 2. The priory finally came into the King's hands in 1414. The large tombstone with its cross, looking like a sword, is thought to belong to an early Giffard, who went on a crusade.