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The postcoding
system was devised by the Royal Mail to enable efficient
mail delivery to all UK addresses. Initially introduced in
London in 1857 the system as we now know it became
operational for most of the UK in the late seventies.
Today the Royal
Mail deliver to over 28 million addresses (also known as
"delivery points")
There are
approximately 1.8 million unit postcodes in use and so each
postcode covers an average of about 15 properties,
however in reality it can be anywhere between 1 and 100.
Organisations
that receive large volumes of mail are allocated individual
postcodes. These are known as "Large User" postcodes and
include PO Box addresses.
Postcodes are
not static. New properties are constantly being built, old
ones demolished, and the Royal Mail sometimes has to re-code
within existing areas to maintain or improve distribution
efficiency. So postcodes are added, deleted, and in some
cases changed on an ongoing basis.
|
GU |
16 |
|
7 |
PW |
|
Area |
District |
|
Sector |
Unit |
The postcode
system is hierarchical, the top level being postcode area -
1 or 2 alpha e.g. "GU" or "B". For a complete list of postcode
areas
click here.
The next level
is postcode district e.g. "GU1" or "B22". This is also
commonly known as the "outcode" and generally provides the
primary bulk sorting office routing information for the
Royal Mail.
Next comes
the sector e.g. "GU16 7", and then finally the unit e.g.
"GU16 7PW". The combination of sector and unit (the "7PW" bit) is often called the
"incode" and is used by the
delivery offices to get the mail on the right vehicle (or
bicycle) for final delivery.
The latest
quarterly release counts can be found in the right column.
Please note that
whilst the "inward" part of the postcode is always 1 numeric
character followed by 2 alpha the "outcode" can be several
different formats and anywhere from 2 to 4 alphanumeric
characters long.
To uniquely
identify each property within each unit postcode and to
facilitate fully automatic sorting of bulk barcoded mail the
Royal Mail use an additional code called the "Delivery Point
Suffix" This code (one numeric + 1 alpha e.g. "9Z") is not
divulged to the general public and only used in bulk
barcoded mail applications.
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