It sits on a clay ridge shared with Basildon and Hadleigh, 31 miles (50 km) east of Charing Cross, London.

A third Anglican church is in the secular ward of St John's, which is commonly conflated on maps with South Benfleet which it adjoins and it is separated from Thundersley by a narrow green buffer.

[1] Thundersley derives from the Old English Þunres lēah = "grove or meadow [perhaps sacred] belonging to the god Thunor or Thor".

The area is relatively hilly for Essex, a typical height for the central and eastern part of (old) Thundersley is about 200 feet (60 m) above sea level.

[5][n 1] Samuel Lewis's major work, a Topographical Dictionary of England in 1848 gives this account: THUNDERSLEY (St. Peter), a parish, in the union of Billericay [...] S.[outh] division of Essex, 2¼ miles (S. W. by W.) from Rayleigh; containing 596 inhabitants, of whom 120 are in the hamlet.

The church is a venerable structure in the later Norman and early English styles, with a tower and spire.

Initially the bikes were an offshoot of the Invacar company, which produced invalid cars and needed to diversify its products.

There are two tiers of local government covering Thundersley, at district and non-metropolitan county level: Castle Point Borough Council, based on Kiln Road in Thundersley, and Essex County Council, based in Chelmsford.

80 locomotive Thundersley was named after this area, and it is on exhibition at Bressingham Steam and Gardens in Norfolk, on loan from the National Railway Museum.

There is one park located in Swans Green Recreation Ground, along Hart Road and another at Thundersley Great Common.

Thundersley Christian Spiritualist Church was formed in October 1933 and moved to a wooden hut on Bread and Cheese Hill in July 1947.