The accepted system of the 39 traditional counties arose from the 12th to the 16th centuries, though many of the specific areas are much older. They became established as a geographic reference frame over time. There is some dispute as to whether an Act passed in 1844 to simplify the counties by reducing the many exclaves should be accepted or not.
There are now exactly 82 administrative counties, if Greater London is included. Of these, 35 are 'shire counties' with county councils and district councils, and 40 are unitary authorities. Six are metropolitan counties. The remaining one is Berkshire, whose county council has been abolished and its districts have become unitary authorities.
A proposed local government reform involving the creation of elected regional assemblies may lead to another round of changes to the administrative counties in 2005 or 2006.
The ceremonial counties are the areas covered by a Lord-Lieutenant. Historically these largely coincided with the traditional counties, but with the addition of the City of London and the City and County of Bristol. They broadly followed the administrative changes, although for example East Suffolk and West Suffolk were a single ceremonial county, Suffolk.
These counties were adopted as the usual geographic reference frame. In 1974 when the administrative counties were reformed, the ceremonial counties were made to match these exactly.
After the local government reforms in the 1990s, certain areas that became unitary authorities were returned to their original ceremonial county. These counties are probably the ones most commonly in geographic use, although many people still use the 1974 ones.