Harwell is a village and civil parish in the Vale of White Horse about 2 miles (3 km) west of Didcot, 6 miles (10 km) east of Wantage and 13 miles (21 km) south of Oxford. The parish measures about 3.5 miles (6 km) north – south, and almost 2 miles (3 km) east – west at its widest point. In 1923 its area was 2,521 acres (1,020 ha). Historically in Berkshire, it has been administered as part of Oxfordshire, England, since the 1974 boundary changes. The parish includes part of the Milton Park business park in the north and part of Harwell Science and Innovation Campus in the southwest. In the east it includes part of the new Great Western Park housing estate that is contiguous with the built-up area of Didcot. The 2011 census recorded the parish's population as 2,349.