Since their introduction in 1959, postcodes have become more than just a tool to sort mail. They help to set the value of our homes, define us as citizens and affect our lives in all kinds of surprising ways. Those little series of letters and numbers at the end of our addresses were created to help letters and parcels to find their way more quickly and efficiently into our letterboxes. Somehow, though, they’ve ended up putting us all into slots of our own. They are used to categorise us and predict our shopping and voting patterns. And they can influence the trajectory and quality of our lives, as the postcode we live in can often govern our education, healthcare — and our house price.
London had been divided up into postal districts by compass points (N, E, S, W etc) from as far back as the mid 19th century. After the Second World War, however, the constant growth in national mail volumes — 28 million letters and parcels a day by 1960 — dictated the need for a scheme whereby the whole of Britain’s post could be sorted by machine, rather than by hand. A similar version of the system we use today was first trialled in Norwich in 1959. After a few tweaks here and there, it was rolled out countrywide in 1965 by Tony Benn, then postmaster general.
There are now about 1.8 million individual postcodes in the UK divided into 124 areas, of which the largest, IV (Inverness) covers 6,243 square miles. The smallest, WC (West Central London), by comparison, contains just one square mile. Those areas are then broken down into districts, then again into sectors and finally into an individual postcode which represents, on average, 17 addresses, or “delivery points” (your home).
When it was introduced, this complex new system relied on recent advances in computing technology and it was here where the real innovation took place, according to Chris Taft, curator of a new exhibition, Sorting Britain: The Power of Postcodes, at the Postal Museum in London.
“The postal service was miles ahead of the game when it came to technology,” Taft says. “Their Dollis Hill research station in northwest London built Elsie [Electrical Letter Sorting Indicating Equipment], the machine that significantly sped up the reading and processing of handwritten addresses.”
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The original Elsie — on display in the exhibition — could process 6,000 letters an hour but modern Intelligent Letter Sorting Machines (ILSMs) are more than six times faster. “A post office engineer called Tommy Flowers worked at Dollis Hill and designed Elsie’s predecessor, Colossus. It was the world’s first programmable computer and built for use by the British military in the Second World War. Flowers’s help had been specifically requested by Alan Turing at Bletchley Park and Colossus was used to decipher communications between Hitler and his high command. So, essentially, the post office invented the modern computer and helped us to win the war.”
Unlike private car registrations, it’s not possible to buy a bespoke postcode for your home. “Very large companies sometimes have their own postcode, such as the Royal Mail themselves who tend to keep all the 1HQ codes for their regional headquarters,” Taft says. “The postcode suffix AA in each area of the country is usually reserved for the district’s main post office. There are a few exceptions, though, the most notable being SW1A 1AA. which belongs to Buckingham Palace.”
These days, the right postcode can make all the difference when it comes to the battle of buying and selling property. Despite being the country’s smallest, WC is also the postcode area that’s had the biggest increase in average property price over the past decade: up 87 per cent to £1.043 million according to Savills estate agency. In the most recent five years, however, Savills reports that M (Manchester) and NE (Newcastle) postcodes have performed the best, with prices up 43 per cent and 57 per cent respectively.
“Even in the most expensive parts of the country, some postcodes are much more aspirational than others,” says Lucian Cook, Savills’s head of residential research. “This is largely determined by location, with homes in postcodes offering sea views, close proximity to the best commons and parks and the most fashionable high streets, all demanding larger price tags than their neighbours. This often means that buyers can find themselves paying significantly more than another buyer purchasing just a few roads away.”
Cook says the largest difference between average values within a postcode can be found in the West London postcode district, with buyers paying a premium of more than £5.5 million to live in the best area (which is W1B; as opposed to W7, the least expensive in that district). Price gaps between postcodes are not limited to the capital. Homes located in Manchester’s inner city postcode area (M1) can garner as much as a 30 per cent premium, while buyers can pay 26 per cent more to live on the best roads in Cambridge (CB).
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Andrew Cronan, head of the estate agency Strutt & Parker’s Bath office, reports different findings: “In a built-up area such as Bath, the difference between BA1 and BA2 is negligible. It’s not the last line of your address that matters, but the first, be that the Royal Crescent, Circus or Lansdown Crescent, which delineates the prestige of where you live.”
It’s not just estate agents and insurers who rely on postcodes. Professor Richard Webber is a geodemographic scientist working at the intersection of marketing, geography and social sciences. In the 1970s he devised a software program known as Mosaic, which combines information published by the census with data from other sources, such as the electoral register and supermarket loyalty schemes, to build a detailed picture of consumer habits and behaviour in every British postcode.
While it doesn’t hold any personal data about individuals, the program categorises us all into 61 distinct types. These range from the fairly self-explanatory “corporate chieftains” at the top, through the beleaguered ranks of “burdened optimists”, right down to “low horizons” somewhere near the bottom. The labels have been altered by Experian — the consumer credit reporting company that now owns Mosaic — over the years to reflect changes in how we live, but the system is still very much in use today. Banks, charities, political parties and retailers use Mosaic’s postcode-based classifications for everything from finely tuning their advertising campaigns to deciding what kind of food to stock in your local supermarket. After all, there’s probably not much point trying to flog bottles of Krug and caviar to a load of “bedsit beneficiaries”.
Speaking from his home in a leafy part of London’s N6 — putting him firmly in “cultural leadership” territory — Webber says: “The postcode works very well as a data provider because what retailers are often really interested in is not just the individual consumer but what their neighbours are like”. That may sound paradoxical but, as he explains: “When you choose where to live, you’re attracted not just by the property itself but also by the streets around it. So, in that way, a neighbourhood tends to attract people who will fit in. But what’s not so recognised is that once you move into a neighbourhood, you are more exposed to certain cultural attitudes than you would have been if you’d moved somewhere else. You grow to become more like your neighbours. That’s why you may have two people who are identical in terms of personal demographics (same age, background, income, job etc) but if they live in different neighbourhoods they will behave very differently, have different aspirations and buy different things.”
Webber, co-author of The Predictive Postcode, recalls the experience of demonstrating his program to potential buyers: “People would input their postcode and then read the description of the kind of person the program told them they were. Very often they’d say, ‘That doesn’t describe me very well, but it does sound an awful lot like my neighbours.’ ”
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Sorting Britain: The Power of Postcodes runs from March 30 until January 1, 2023 at the Postal Museum, 15-20 Phoenix Place, London WC1. For details, visit postalmuseum.org
