Two hundred years ago Cornwall was largely governed by Cornishmen living in Cornwall. There was, of course, a national government in London that made the rules, but the implementation and enforcement of these laws was mainly in the hands of Cornishmen. They were, of course, largely drawn from the upper and middle classes.
There were no district or county councils. The representatives of The Crown were here; they lived here amongst the Cornish. Lord Leuitenants, High Sherrifs and Judges enforced the laws laid down in London. At the lowest level was the Ecclesiastical parish, ruled by the local vicar. The parish had acquired various civil functions over the centuries, and the Vicar was constrained by law and by the elected Vestry. The Vestry was more or less self-selected from amongst the more prosperous inhabitants of the parish, but in the last resort they depended on the support of the parishioners.
From the time of the Tudors, the civil parishes (which usually covered the same ground as the ecclesiastical parishes) were given powers & duties governing the poor, the highways and petty crime. The system was supervised by the judiciary through the Quarter Sessions. At the same time, the manorial system was still around in many areas, with its own courts. The Court Leets & Baron were still meeting late in the 19th century and these appointed officials for such things as Ale tasting and Bread weighing. One of the chief officers was the Constable; he was responsible not only for local law and order, but for collecting local taxes such as the poor rate. Elected Parish Councils arrived in 1894, after the formation of County Councils.
Throughout the 19th century, the government in London refined the laws relating to social order and public good. New obligations and new rights were set out. But it is a mistake to see this entirely as a top-down process. There was pressure from the bottom to change things. A good example is the Poor Law Unions and the associated workhouses. The groans of those paying the poor rates forced the government in London to do something. The workhouses were sited, built, manned and maintained by local boards. There was a local board of governors and the jobs and the contracts to supply and maintain the workhouses were advertised in local papers.
By the end of the 19th century, elected County and parish councils had arrived. In the towns there were borough councils and in between the county & parish councils were Rural & Urban district councils. In 1830 Cornwall had more Members of Parliament than any other English county except for Wiltshire. These two counties had more MPs than Scotland! But in 1832, the reform act swept all that away and Cornwall was reduced to six. My own village had returned two MPs for 200 years. In the election of 1830 there were only 7 electors and they managed to elect three MPs instead of two!
In spite of constant change, much of the basic structure of Cornwall remains the same as it has been for a thousand years. Although I live in the modern district council area of Carrick; it covers almost the same ground as the ancient Hundred of Pydar. The parish of Newlyn East has been where it is for over a thousand years. The village of Mitchell is first recorded on paper in a court case of 1234 AD. The four local Domesday Manors of 1086 are still the sites of farms today.
Since the 1980s there has been increasing centralisation with more control going to outposts of the central government in regional authorities. The South West one lives a long way from Cornwall. The police force merged with that of Devon and the fire service is to be controlled from Taunton in Somerset. Even higher up, more and more power is shifting from London to Brussels and the County Council now has an office in that city.
Whether the shift from Cornwall to Swindon, London & Brussels is a good thing is an argument for another day!