Londons Postcodes (ZIP Codes)

London Postcodes: a History

Postcodes are a London obsession. Decades of snobbery have revolved around whether your area of residence has a postcode respected by the upper echelons of London society. House prices in the capital are mainly defined by location and Londoners regularly pay above the odds to acquire desirable postcodes.

Prior to the introduction of postcodes London’s mail was often vaguely addressed and deliveries were erratic. The population growth spurt of the mid-nineteenth century created a need for a more ordered system and initial reforms were introduced which renumbered 100,000 houses and renamed 4,800 areas.

Problems persisted though and eventually a former teacher with a passion for the post hit upon a solution which divided the capital into 10 separate postal districts. Sir Rowland Hill’s system was based around compass points and an office established for each district which were organised and contained within a circle of 12 miles radius from central London.  Sir Roland was later made Secretary to the Postmaster-General in 1846 and continued to reform the Post Office until his retirement in 1864.

Between 1857 and 1858 the circulation of London’s mail improved immeasurably due to Hill’s scheme. The public were required to add the initials of their districts to the end of an address and local letters could now be sorted in the local office instead of being taken to the Chief Office in the centre of London. In 1866 a report by the surveyor, Anthony Trollope, who later became a revered novelist, lead to a re-ordering of the districts with the North East area merging with the East district.

London’s postal revolution sparked off similar reforms in other major towns, such as Manchester and Sheffield, where the initial of the town name was used and followed by the number of the geographical district. Further refinements were introduced during World War I to aid women who had taken over the sorting work while the men were at war.

Their lack of experience lead to an attempt at simplification and the introduction of sub-districts which were all given a serial number. For example the Eastern District Office was E1, Bethnal Green was E2, Bow was E3 and so forth.

This added a degree of clarity but it remained a complicated task for the uninitiated as London postal districts rarely coincide with borough boundaries. The numbering system also appears to be relatively random when looked at on a map. For example, NW1 is close to central London, but NW2 is much further out. This is because they were numbered alphabetically by the name of the district they represented. Also as the city has sprawled a further gradation has been introduced in some central London areas, producing unusual codes such as EC1A 1AA.

More confusion derives from some London areas using postal addresses that refer to former county boundaries, for example postal addresses in Sutton traditionally read "Sutton, Surrey" and not "Sutton, London" even though Sutton no longer falls within the boundaries of Surrey County Council. And some of the postal districts cross county and even regional boundaries - the KT postcode covers areas in both Greater London and the South East Region.

The system remained in place until technological improvements in the early 1960’s kick-started a major mechanisation programme. Machines replaced manual workers across the nation with postcodes being reduced to a machine readable form and printed on the envelope in phosphor dots. The present postcode system was introduced at Croydon in 1966 and finally completed in 1974 with the recoding of Norwich.

The mid eighties saw the introduction of an Optical Character Recognition (OCR) system which is the basis of the current mail sorting procedure. This system automatically reads the postcode on printed addresses and prints the appropriate phosphorescent dots (codes) on the envelopes. This replaces the need for operators to key in the postcodes by hand and massively speeds up the whole process. Integrated Mail Processors introduced in 1997 completed the processing system. One machine now processes mail from arrival in the Mail Centre to its final destination.