The home counties are the
The origin of the term "home counties" is unknown and no exact definition exists, making their composition a matter of constant debate.
The earliest use of the term cited in the
Later definitions have tended to be more narrow and Bacon's Large Scale Atlas of London and Suburbs (revised edition c. 1912) includes Berkshire, Buckingham, Essex, Hertford, Kent, Middlesex and Surrey in the "maps of the home counties". 
The term is sometimes understood to mean those counties which, on their borders closest to London, have been partly subsumed into London. Indeed, the former county of
The third edition of the Oxford English Dictionary (2010) defines the term as "the English counties surrounding London, into which London has extended. They comprise chiefly Essex, Kent, Surrey, and Hertfordshire."
 Parts of all of those historic counties are, since 1965, officially within London, although no part of Berkshire, Buckinghamshire or Sussex is. The county of Sussex is also wholly outside, and Berkshire almost wholly outside, the route of the
Theories sometimes mentioned for the origin of the term include the idea that the home counties were where the wealthy of London had second homes, the counties that members of parliament returned to after the end of business, or the counties in which regular commuters into London lived. An additional theory is that the term derived from the Home Circuit of the