It has been claimed that the single most important event in Britain's history occurred millions of years ago, or whenever it was during the formation of the earth's surface that the English Channel and North Sea were formed, separating the British Isles from the continent of Europe. Certainly the fact that the mainland of Great Britain, comprising England, Scotland and Wales, is an island has been of central importance to its development as a nation. Thus the isolation of the British made their history, in some respects at least, different from the rest of Europe's.

One of the crucial differences was the county. Until the Local Government Act of 1972, which became effective in 1974, England and Wales were divided into fifty-two counties and Scotland into thirty-three. In the eighteenth century the English counties were administrative units. Each had a sheriff, a commission of the peace, and a militia presided over by a lord lieutenant. The post of sheriff was irksome and expensive, and men tried to avoid selection for it. By contrast the offices of justice of the peace and deputy lieutenant of the militia, though they were unpaid, were coveted since they bestowed status on their incumbents. The justices administered a great deal of statute law, either singly, in pairs, or collectively, at the sessions held every three months and therefore called quarter sessions. They would refer the most serious cases, involving capital crimes, to the assizes, generally held twice a year in the county town, when a judge from one of the common law courts at Westminster would preside over the trials.