Administrative division of the British Islands (Cromwell the Great)

The Union of England, Scotland and Ireland, established by several Ordinances and Acts of Parliament (Scotland 1652, 1654 and 1657, and Ireland 1665) created a common political union in the Commonwealth, dissolved the independent parliaments of Scotland and Ireland, established religious toleration across the three nations (excluding Catholics and episcopalians), the Church of Scotland is recognized as a national church, forfeited all royal property and revenues, established a free trade and customs union, representation in the Commonwealth Parliament, the legal system and courts of the three nations to be maintained and guaranteed their independence, taxes and levies to be harmonized and the contribution of the three nations to be proportional, servitude and vassalage abolished, local barony courts and heritable jurisdictions and similar are abolished, establishment of sheriff's courts (Scotland) and Justices of the Peace (England, Wales and Ireland).

Counties and parishes
The Commonwealth is organized in counties (shires in Scotland) and below it parishes. All have judicial, tax collection and local administration functions, and also are in charge of poor relief. Boroughs (burghs in Scotland), are towns (toun in Scots) that have autonomous corporate entity. For example the City of London and its City of London Corporation. The Isle of Man and the Channel Islands have self-government and are organized differently than the rest of the British Isles.

County government and business is done in the main courts of quarter sessions or quarter sessions, that local courts traditionally hold at four set times each year, however the more populous counties usually hold them more often. Some of the English counties had major subdivisions. Of these, the most significant were the divisions of Yorkshire in three ridings. The second largest county, Lincolnshire, was divided into three historical parts.

County commissioners and shire guardians
A chief innovation was the establishment of county commissions for keeping public peace in England, Wales (both in 1562) and Ireland (1570) and shire guardians in Scotland (1566). Unlike the mechanisms of the rule of the Major-Generals (August 1655 – January 1657) they were attached to each the county in way that was not alien to already existing administrative machinery and with less emphasises in a moral crusade or godly government.

In England and Wales the County Commission is integrated by a County Commissioner and with one to five Deputy Commissioners, all appointed by the Council of State. Its tasks are to enforce the acts, ordinances and instructions of the Parliament, Lord Protector and Council of State. The are to keep public peace and security, suppress disorder and banditry, and promote moral reformation. Help in implementing, tax collection, judicial administration, supervise and qualify justices of peace, sheriffs, bailiffs and high constables and constables. They also chair quarter sessions, coordinated the maintenance and building of roads, bridges and schools and promote literacy. Its military tasks are to organize and train a local militia. They can mediate or refer it to law courts in differences or disputes of county and boroughs or other interest parties or refer it to law courts.

In Ireland the County Commission, is integrated by Commissioner and five deputy commissioners, all named by the Council of Ireland. It has the sames tasks as in England and Wales, however one of the deputy commissioners is chief commander of the militia.

In 1667 Scotland follow a similar scheme with the establishment of the shire guardians. The shire guardians, 3 to 14, are appointed by the Council of Scotland, and included ex-officio members of the shire judiciary. They are to keep public peace and security, suppress disorder and banditry, and promote moral reformation. Their responsibilities are to collect taxes, of highways and bridges, train and command the local militia, supervise high constables and constables. In education they must promote schooling and literacy. They can mediate or recourse to law courts feuds and disputes between highland clans, counties, burgs or parishes of the Church of Scotland. They also help and assist the kirk and baronial courts.

Lord Presidents of Ireland
For Ireland the offices of the Lord Presidents of Munster and Connacht were kept and new ones created for the other two provinces (Ulster and Leinster). The Lord President is subject to supervision of the Lieutenant Governor and the Council of Ireland. Has full authority within the province, extending to civil, criminal and church legal matters, the imposition of martial law, make official military appointments, and command of military forces.

The Isle of Man and the Channel Islands
The Act organizing the Isle of Man and the Channel Islands (1660s) incorporated and reorganized the former Crown dependencies of the Isle of Man, and the Bailiwicks of Jersey and Guernsey, the latter two united as the Channel Islands. Religious toleration is established and the forfeiture of all royal property and revenues. All customs and excise taxes between the Commonwealth and the former crown dependencies are abolished, taxes and levies to be harmonized and the contributions to be proportional. The legislatures of Man and Channel Island were kept and the former dependencies would have representatives in the Commonwealth Parliament. The power to pass legislation and ordinances affecting the Islands ultimately rests with their own legislative assemblies (the unicameral States of the Channel Islands and the bicameral Tynwald of Man) and executives councils, with the assent of a special committee of the Council of State, that also names the Governors. However local laws prevails, unless specified otherwise. The judiciary of the former Crown dependencies is kept independent and the right of appeal to the High Judicial Committee.