Canvey Island, United Kingdom

In 1607 the Elizabethan antiquarian William Camden noted in his work Britannia (a topographical and historical survey of all of Great Britain and Ireland) that Canvey Island (which he called Island Convennon) was documented in the 2nd century by the Alexandrian geographer Ptolemy. In his work Geographia, Ptolemy mentions a headland in the mouth of the Thames to the east of the Trinovantes region called Counus Island. However, the difficulties faced in determining the location of land areas in Ptolemy's ancient work have led modern researchers to question the correlation between Ptolemy's island and contemporary Canvey. MacBean and Johnson, 18th-century historians, contend that Counus Island would have existed much further out to sea (or may even have been the Isle of Sheppey), so any similarity between the names is mere coincidence. Without any suitable island matching Ptolemy's Counus Island, 20th-century historians White and Yearsley posit the documented island to have been lost or reduced to an insignificant sandbank by subsidence and the constant effects of the sea.

The settlement and agricultural development of Essex by the Saxons from the 5th century saw the introduction of sheep farming, which would dominate the island's industry until the 20th century. After the Norman conquest the area of Canvey was recorded in the Domesday Book as a sheep-farming pasture under the control of nine parishes across south inland and coastal Essex; some of these parishes were on the adjacent mainland, but others were as far afield as Laindon and Prittlewell. Apart from the meat and wool produced from the sheep, the milk from the ewes was used for cheese-making. The abundance in later centuries would see the cheeses become a commodity taken for sale at the London markets, and at one stage exported via Calais to the continent.

The existence of several place names on modern Canvey using the wick suffix (denoting the sheds in which the cheese was made) shows the influence of the early Saxon culture. Historian Ian Yearsley states that the name of the island is derived from the Anglo-Saxon Caningaege, meaning "the Island of Cana's People". Developments in the English language yielded the more familiar form Caneveye found in manorial records of 1254. The period of transition from Old to Early Middle English often give rise to confusions of orthography, leading, in this instance, to such variant spellings as Canefe, Kaneweye, Kaneveye and Koneveye. By the 12th century, Essex and subsequently Canvey were in the possession of Henry de Essex who inherited the land from his grandfather, Swein, son of Robert fitz Wymarch. During the reign of Henry II (1154–1189) the land was confiscated from de Essex and redistributed among the King's favoured nobles.

During Edward II's reign (1307–1327) the land was under the possession of John de Apeton and the first attempts were made at managing the effects of the sea with rudimentary defences, but periodical flooding continued to blight the small population of mostly shepherds and their fat-tailed variety of sheep for a further 300 years. William Camden wrote of the island in 1607 that it was so low that it was often quite flooded, except the hills, upon which the sheep had a place of safe refuge. The uniform flatness of Canvey suggests that these hills are likely to be the red hills of the Roman saltmaking industry, or the early makeshift sea defences constructed by some of the landowners around their farms.

In 1622, Sir Henry Appleton (a descendant of John de Apeton) and Canvey's other landowners instigated a project to reclaim the land and wall the island from the Thames. The scheme was managed by an acquaintance of Appleton's – Joas Croppenburg, a Dutch haberdasher of Cheapside in London. An agreement reached in 1623 stipulated that in return for inning and recovering the island, the landowners would grant a third of the land as payment for the work.

The presence of the Dutch engineer Cornelius Vermuyden, a relation of Croppenburg's, in England at the time of the project on a commission to drain the Fens and involved in repairing the seawall at Dagenham, has led to speculation that Vermuyden oversaw the project, but proof appears to be vague; nevertheless, the work was completed by around 300 Dutch workers skilled in the construction of dykes and other sea defences. The engineers successfully reclaimed 3,600 acres (15 km2) by walling the island with local chalk, limestone and the heavy clay of the marshes, with the main length along the Thames faced with Kentish ragstone.

A broad drainage ditch was dug inland off the area facing the river while smaller inlets were filled in. Excess water would have collected in the broad ditch and then been discharged into the river by the means of seven sluices (later known as Commissioners Dykes). The completion of the work saw a considerable number of the Dutch engineers take land as payment for their work, and consequently settle on the island.