In this series of blog posts, Peter Sutton, PhD candidate researching the post-war history of technology and industrial relations in the British Postal Service, offers some reflections on the history of the modern postcode. The significance of the postcode and its origins in the post-1945 era are considered followed by some archival examples tracing different aspects of its design along its journey from a specialised engineering concept to a universally recognised geographical referencing tool.
As mentioned in previous posts, the GPO’s design of the modern postcode became, after the Second World War, a systematic, long-term project which was part of wider attempts at designing sorting machines for a future national sorting system based on new technology. The vision outlined by leading engineers and postal experts in 1946, when sorting was predominantly done by hand at the sorting frame, was of a future system in which the national flow of mail would pass through large, mechanised sorting offices containing machines capable of “reading” each address. Their ultimate goal was to have human labour largely replaced within a generation by the new system, in which the public would cooperate by adding a code when addressing their letters to enable both interpretation and handling to be processed by machines.
As we have seen, as both postmen’s wages and the national volume of mail continued to rise over this period, there was good incentive to pursue these aims and to make what was termed the “code-sort concept” a reality. In the 1950s, the formative years of postal coding theory and practice, new lines of research pursued by GPO engineers helped lock particular characteristics into today’s familiar alpha-numeric postcode, as records held by the BPMA make clear. In particular the files of the Mechanical Aids Committee (MAC) and its subcommittees, which guided GPO policy on letter mechanisation and postcoding, show that choosing from many possible alternative code designs was no simple business.
One aspect of 1950s postal engineering involved trying to understand the psychological processes at work during the act of sorting letters when operating the new experimental machines then being trialled. This was an important step in both the development of the postcode and also in the GPO’s understanding of the so-called “man-machine interface”. Although at the outset it was hoped optical character recognition technology (OCR) might develop to the point of being able to reliably “read” handwritten postcodes, it was known early on that this was decades away at best. Machines for preparing and stacking the mail were then in development and, through an intricate arrangement of rollers, belts, diverters and memory storage, there were excellent prospects for an economical and reliable automatic sorting machine.
The problem was uniting these two phases of sorting – initial preparation of mail entering a sorting office into uniform piles followed by automatic sorting of that mail for particular destinations. In the absence of OCR, people stationed at keyboards (the man-machine interface) would still be needed to read the postcodes on letters and mark each with the correct machine-readable binary imprint. In any national code-sort system this would mean many millions of keystrokes every working day which placed a great financial premium on finding the most efficient arrangement of characters when designing the optimal postcode. A format acceptable to the public and major commercial mail users and also capable of accommodating the required address information was needed. But of no less importance was arriving at a format agreeable to the postman at his keyboard. An optimal format needed to encourage the most efficient possible coordination of hand, eye and brain.
A key figure in this regard was Sir Gordon Radley who took over the Mechanical Aids Committee (MAC) in 1955. This coincided with his appointment as Director General (Secretary to the Post Office), the first engineer to hold this office. Born in Birmingham in 1898, Radley gained his Doctorate in Engineering and served with the Royal Engineers during WWI. He joined the GPO in 1920 where he gained successive promotions through the Engineering Department. During WWII he and fellow telephone engineer Tommy Flowers made significant contributions to code-breaking at Bletchley Park and the design of “Colossus”. He spent ten years as Controller of Dollis Hill Research Station, the GPO centre for technological research, where he earned international fame for leading the development of the first transatlantic submarine cable and helping to invent the hearing aid.
When Radley chaired his first MAC meeting on 16 November 1955, he spoke of injecting more efficiency and pro-activity into the mechanisation field, issuing tighter deadlines and drafting in more senior staff. He oversaw the continuation of various long-term lines of technical enquiry and wished to see quicker progress in the development of postcodes, identifying the coding of letters by fluorescent marks as a priority project. Here, he encouraged Mr. A. Crisswell, a Deputy Regional Postal Director who headed the coding study group, to take a more liberal approach and worry less about the financial prospects of new ideas. Crisswell was directed to increase collaboration with operational experts in the Postal Services Department and to specify the desired characteristics of a code and to consult mathematicians specialising in coding theory.
Radley’s personal intervention into developing codes came as a series of questions posed in April 1956. A series of field trials with the Single Position Letter Sorting Machine (SPLSM) were then underway at Bath. There, postmen were trained to operate the machine’s keyboard to which letters were presented for processing, in which a memorised list of two-letter codes (denoting counties and towns) were added to the letters based on their addresses at between 32 and 52 items per minute. Their movements were filmed and then timed and analysed, prompting a series of questions on the MAC about how to deal with this data, with Radley leading the way. “Which kinds of codes are easiest to learn and use?” he asked. “What is the relationship between number of codes in a series and learning time?”, “What is the relationship between coding time and the number of possible codes to choose from?”, “How long does plural coding take relative to simple coding?” and “What is the best training method?”.
Such precise questions were used to direct new lines of research on the MAC as they sought to evolve better and better machines for letter sorting, of which the coding position was a vital “link”. The Bath trials and the manner in which their results were put to use by GPO engineers is just one early episode in a long history of ergonomic design for coding desks and added to a body of research into the physical and mental demands made upon postmen who sorted the mail. Radley’s questions might also be seen as illustrating the diversity of factors at play in choosing the most suitable code for the British postal service.