Directories have been published since the seventeenth century, but it was
in the 19th century that the number published significantly increased and
that private persons began to be regularly included.
The directories were
frequently produced by private concerns, such as Kelly and Pigot, and
the area covered varies greatly from the whole country to just a single
county. Details within specific counties are generally divided alphabetically
by town or rural parish. The entry for each town, usually starts with a
brief history and description of the town followed by persons holding
official postions, gentry and finally trades persons (frequently arranged
by occupation).