TELEGRAPHIC CODES and POSTCODES

Telegraphic codes
Telegraphic codes originated in the earliest days of electric telegraphs as an efficiency measure, to reduce the number of characters needed to signal another station on the same circuit. In those days the telegraphs were run by private telegraph companies and by the railways. When public messaging traffic was nationalised in 1870 it was natural that the Post Office should adopt and retain these codes, and over the years both the Post Office and railways expanded the number of codes in use.   When the BBC and other broadcasting organisations came into being later, they rented many private circuits from the Post Office and for convenience they used the same codes. Consequently today we have three separate industries, railways, broadcasting and telecommunications all using the same codes to denote places.

Finding lists of these codes is difficult and only the BBC issues a codified list of what it calls Location Codes. On the railways these codes are used mainly by tradition and there is no official list today as far as the compiler knows. Whether BT still issues a formal list of these codes is also unclear but they are still very much in use. Exactly comparable codes are also used in New Zealand and probably also in other countries that follow British practice.    

HOW TELEGRAPHIC CODES WERE USED
For each circuit a system of code calls was devised for all the stations in circuit and to call up a station the code call was given. Most codes consisted of two letters, often the first and last letter (e.g. EH for Edinburgh) or the initial letters of two syllables (e.g. NH for Northampton). When these had run out, other memorable combinations were used such as PE for Peterborough, IG for Brighton, IM for Birmingham Snow Hill and JO for Nottingham Joint station (Victoria). However, with only 650 combinations of two letters of the alphabet and a much larger number of telegraph stations problems inevitably arose.

On the railways some of the more important offices would be denoted by single letters alone for simplicity's sake (e.g. L for London Bridge SECR), and generally speaking confusion did not arise from duplication of code calls, for even though a given two letter code might denote two different places these would not be in direct communication with one another.  

Less frequently and mainly in densely stationed areas three letter codes were resorted to (e.g. WDN for Willesden Junction and HRN for Herne Hill). Generally the letters chosen appeared in the name of the station, although resort had to be made to cyphers and other meaningless combinations once all the logical combinations had been used up (thus Z for Slough and VL for Birmingham Snow Hill Down Office).  

On the Post Office different conditions obtained. Since most circuits were short and sub-offices communicated only with their main office some simplification of code calls could be made. Moreover, code letters frequently and carelessly repeated could sound like words, and an inattentive station might conceive that a message was being transmitted between the other stations instead of his own station being called. In view of this single code letters were allotted to sub-offices, namely D, G, K, O, R, S, etc. applied down from the head office. For example:

Maidstone	MA
Hollingbourne	D
Lenham	G
Egerton	K
Charing	O
Ashford	AD

It is no coincidence that the same codes MA and AD were used to denote Maidstone and Ashford on the railway telegraphs also. The actual choice of letters was made in the early days of telegraphy when many commercial telegraph routes followed railway lines and before the Post Office took over these companies.  As a result the Post Office inherited the original codes and this explains why in later years the same codes were being used by both the Post Office and the railways.      

ENGINEERING CODES
These codes served as useful abbreviations and although no longer used for telegraphic purposes still serve a convenient purpose to identify specific locations in some quarters of British Rail and British Telecom (long after the old telegraphs disappeared). Within BT they are now termed Engineering Codes, supplemented by many additional codes that have been created as necessary over the years. Some of these have somewhat obscure origins - for instance the new town of Basildon (Essex) has the engineering code JSL, which got its name because it was at the junction of the cable to South Benfleet, code SL, hence JSL. No doubt many of the codes had simple derivatives and were added as the network grew.   For conformity, the BBC and NTL (National Transcommunications Ltd, previously the Independent Broadcasting Authority) also use some of the same codes for engineering purposes. The BBC terms them Location Codes and has added some new codes of its own.

POSTAL USE
The codes that originally served to identify offices that transmitted and received telegrams were also adopted for a wide variety of non-telegraphic purposes by the Post Office. In the book referred to below, the author states these codes were widely used on parcel labels from 1883-1916 and until 1924 on the date stamps used for cancelling stamps on parcels and printed matter. Other postal uses continued after this date and a glance at the freepost address used by Maplin Electronics Ltd shows that the 'prehistoric' telegraphic code of SMU for Southend-on-Sea lives on to this day.   The best sources of historical information on these codes are the telegraph code lists of the former railway companies (hard to find) and a comprehensive book by James Mackay that lists the complete roster of Post Office codes as in 1909.  

J.A. Mackay: Telegraphic Codes of the British Isles 1870-1924. Dumfries: 1981: self-published. [out of print but still stocked (at time of writing) by Vera Trinder Ltd., 38 Bedford Street, London, WC2E 9EU.]

Postcodes
The only country that has copied Britain's postcodes is Canada, although the position of letters and figures is reversed here, e.g. K0J 2E0.   Listings of British and Canadian codes are here.