There are twelve in total; all have access to the sea and share a name with their ancient parish churches.

The uniformity may in fact be designed out of a reorganisation of the Diocese of Coutances in the twelfth century by Archbishop Geoffrey de Montbrai, following Viking raids of the islands.

The new boundaries paid little heed to the fiefs or to geographical factors (hence why Gorey and St. Aubin are not parish centres, despite being populated).

[2] By Norman times, the parish boundaries were firmly fixed and remain largely unchanged since.

For example, there is the ancient practice of l'ouie de paroisse - the recording of contracts, court decisions and legislation by the parishes.

In 1545, the States set up a system of districts based on parish boundaries for defensive purposes.

Archery ranges, parade grounds and arsenals known as Les Buttes were set up in various parish centres.

The criteria to be considered a principal differed by parish and was determined by the amount of rate paid on property.

[6]: 21 In 1496, Henry VII bribed the Pope to allow Jersey to be moved from the diocese of Coutances to Westminster.

[2] In the 19th century, the Church of England experienced a reduction in its role in civil affairs, including within the parishes.

In accordance with the Loi (1914) sur la Voirie it superintends the repair and maintenance of by-roads in the parish, establishes boundary stones, issues Choses Publiques licenses, examines planning applications that fall within its responsibilities, supervises refuse collection, adjudicates fines during the Visite du Branchage, and proposes new road names, as may be necessary, for approval by the Parish Assembly.

In St Helier, the larger Roads Committee also undertakes additional non-statutory responsibilities with regard to parks and other matters, and acts, in the absence of a municipal council, as an advisory body to the Connétable.

By convention, the two Procureurs du Bien Public of St Helier attend meetings of the Roads Committee, but cannot vote.

Honorary Police officers have, for centuries, been elected by parishioners to assist the Connétable of the Parish to maintain law and order.

The Parish Assembly elects two Roads Inspectors for each Vingtaine [or Cueillette in St Ouen] for a three-year term of office in accordance with the Loi (1914) sur la Voirie.

In the Parish of St Helier, the Roads Inspectors also undertake additional non-statutory responsibilities with regard to the policing of infractions of the Road Traffic Act (Jersey) and other areas of the law within the parochial remit such as dog licensing and fly posting.

Supplementary bodies are also elected to serve specific needs; in the largest parish St Helier these include; the Accounts Committee, the Welfare Board, and the Youth Council.

Matters of import are brought before a gathering of the municipality and members of the public for consideration and vote.