The southern part of the parish was originally a natural salt marsh adjacent to the River Thames which is tidal and saline at this point.

Decaying vegetation together with mud and silt from the river were deposited from the end of the most recent ice age until the marshes were reclaimed sometime before the 14th century.

[2] About two miles north of the river, the land rises steeply to a ridge (extending from Grays to East Tilbury) about 100 feet (30 m) above sea level (AOD) on which most of the Chadwell's housing is built.

[4] The eastern and northern edges of the wood are part of the boundary between the traditional parishes of Chadwell and Orsett.

[4] Biggin is a late medieval hamlet on the edge of the marshes that was part of the traditional parish and remains so ecclesiastically (in terms of Anglican church).

Artifacts found (some of which are in the local museum in Grays) show that the area was inhabited in the Stone, Bronze and Iron Ages.

A Roman oven was found in this location in 1922 containing three complete pots, fragments of others and a small clay lamp, all of which were given to Colchester Museum.

[10] An archaeological investigation during the construction of new facilities for Chadwell Primary school discovered a complete site of a Saxon sunken floored hut (Grubenhaus) from the 6th century.

Since then, the community has economically continued to thrive on fertile soil and good communication links with the outside world over the centuries.

[13] 'St Mary', referring to the parish church, was added to the name in Victorian times to reduce confusion with Chadwell Heath, near Romford.

[14] Thurrock's earliest historian, William Pallin, described the well: "Descending the hill from the venerable church, we find ourselves on the border of the level, face to face with an ancient well, having more the appearance of a tank, wide and shallow, large enough to walk into, just such as the apostolic Chad might be thought to choose for the baptism of his East Saxon converts".

[15] "St Chad’s Well" is shown on the late 19th century 6" Ordnance Survey map, just north and east of the roundabout at the bottom of Chadwell Hill, although, the modern Ordnance Survey map appears to place it a few yards away, just south of Marshfoot Road – roughly on the site of the Gateway Academy.

[13] It is nonetheless a very common name – there are apparently 42 instances of "St Chad’s Well" in different parts of the UK.

[18] The most likely reason is relatively modern confusion about the place name, Chadwell, which means (in old English) "cold spring" rather than having any connection with St Chad.

If the village name had retained its ancient Domesday form, Celdewella, St Chad would in all likelihood be forgotten in Thurrock.

[20] The manor of Ingleby was bought by Peter Symonds in the 1580s and was bequeathed by him to found Christ's Hospital in Winchester.

[21] In addition to founding the school in Winchester, Peter Symonds left annual payments for a number of charitable purposes, including the poor of All Saint, Lombard Street and Chadwell in Essex.

[19] During World War II, Chadwell was at risk from enemy action both because of its proximity to Tilbury Docks and because German bombers used the Thames to navigate to London.

As part of the air raid protection scheme for London, there was an anti-aircraft battery (designated N16) on former heathland just south of the Greyhound pub that was manned by Canadian soldiers.

The place of birth of residents was 96.9% United Kingdom, 0.5% Republic of Ireland, 0.6% other Western European countries, and 2.0% elsewhere.

The industry of employment of residents was 23.9% retail, 14.2% manufacturing, 9.4% construction, 8.8% real estate, 8% health and social work, 5.4% education, 12.2% transport and communications, 3.5% public administration, 4.2% hotels and restaurants, 4.7% finance, 0.8% agriculture and 4.9% other.

[30] In 2007, Chadwell was described by the former local MP, Andrew Mackinlay, as one of the "pensioner hot spots" of Thurrock.

Palmer's Sixth Form College covers Chadwell St Mary and Thames Park Secondary School also covers Chadwell St Mary, although it is just across the parish boundary in Little Thurrock as was the Thurrock campus of the South Essex College of Further and Higher Education before it moved to Grays.

Daniel Defoe, the writer managed and later owned a tile factory on the Tilbury Marshes (part of Chadwell at the time) and lived in a house on the edge of the river.