Ewelme is a village and civil parish in the Chiltern Hills in South Oxfordshire, 2.5 miles (4 km) north-east of the market town of Wallingford. The 2011 census recorded the parish's population as 1,048. To the east of the village is Cow Common and to the west, Benson Airfield, the north-eastern corner of which is within the parish boundary. The solid geology is chalk overlying gault clay; the drift geology includes some gravel.

South Oxfordshire is a local government district in the ceremonial county of Oxfordshire, England. Its council is temporarily based outside the district at Abingdon-on-Thames pending a planned move to Didcot, the district's largest town. The areas located south of the River Thames are within the historic county of Berkshire.