Chadwell St. Mary is now in the unitary authority of Thurrock in Essex, England. It is one of the traditional (Church of England) parishes in Thurrock and a former civil parish. Its residential areas are on the higher ground overlooking the former Thameside marshland. Grays Thurrock (or Grays) is a town centred 2 miles (3.2 km) west of it. Closer still, 1 mile (1.6 km) south is the modern town of Tilbury which was almost wholly within the parish until the end of the 19th century. The settlement is frequently referred to simply as Chadwell, particularly before the 19th century.
The parish was part of the Orsett Rural District from 1894 until 1912 and the Tilbury Urban District from 1912 until 1974. Since 1974 it has been located in the Thurrock District in Essex (a unitary authority since 1998).
For more information, see the EN Wikipedia article Chadwell St Mary.