An overview of the relationships between counties, baronies, civil parishes and townlands can be found on this page.

• The Great Britain Historical Geography Information Service (GBHGIS) provides a mass of information about Britain's localities as they have changed over time. Information comes from census reports, historical gazetteers, travellers' tales and historic maps.
• A Vision of Britain Through Time, in the GBHGIS, provides maps and statistical information derived from census reports covering the period 1801-2001, searchable by place name or post code.
• The Association of British Counties (A.B.C.) "is a society dedicated to promoting awareness of the continuing existence of the 86 traditional Counties of Britain".
• British Counties, Parishes, etc. for Genealogists (archived copy).