From WikiLeaks

September 16, 2009

By Charles Arthur (The Guardian)[1]

Wikileaks is hosting what it says is a copy of the entire UK postcode list, last updated on July 8 2009, that contains "all 1,841,177 UK post codes together with lattitude [sic] and longitude, grid references, county, district, ward, NHS codes and regions, Ordnance Survey reference, and date of introduction. The database ... is over 100,000 pages in size."

The 230MB file, zipped to 20MB, does indeed contain a huge slew of postcodes in comma-separated form, with those details as headers for each column.

Oh my. We have no idea who has leaked this, but it is the gateway to some valuable information: Royal Mail, as we ascertained previously in the Free Our Data campaign, sells the Postcode Address File (aka PAF) for a considerable sum, and makes a good profit on it: in August 2007 the postal regulator Postcomm revealed that PAF operations made a profit of £1.58m on revenues of £18.36m, all but £4m from resellers.

This isn't quite that, however, because the PAF includes the names and/or addresses of houses in each postcode. That would be 28m locations - and that's not what this file includes.

Instead, it's got data that's more useful to government, containing as it does NHS ward data. Update: this seems to be the PostZon database which

allows you to link geographic and administrative data from government bodies, such as local authorities and the NHS, for all known Postcodes in the UK. Use it to help plan routes, calculate distances between Postcodes, allocate sales force areas, distribute resources or locate facilities.

We have asked Royal Mail for a comment, but received none so far.

An early reaction from one web developer I know who uses postcodes to long/lat was not that impressed: "we can get this service free from Google via its mapping conversion system," he pointed out. "And that won't go slowly out of date." (Studies have shown that the PAF adds about 4,000 postcodes each month and drops 2,000 existing ones.)

A good point - and it is worth pointing out too that postcodes can cover large areas of a street or more, so long/lat isn't that useful really, though it might be for route planning. A postcode will tend to be on a single route (rather than two adjoining streets, say); my own home postcode covers about half a mile, so the long/lat is by its nature not exact. (I've checked against this list, and it is the long/lat combination used by satnav systems, for example.) Satnav companies would steer clear of this because they would know there'll be some intentional errors in it which Royal Mail would sue them for using without a licence.

But there are surely web developers all over the country who are downloading it right now just to have a poke around and see if there isn't something useful they could do with it. Free our data? It's certainly gotten it out there.

Update: another web developer says "Google's lookup is not accurate (presumably due to licensing issues), and can only be used if you're using a Google map... Postcode to long/lat is also incredibly useful - it's what powers WriteToThem, TheyWorkForYou, PlanningAlerts..."

The upshot: this is a really useful database, for particular applications. Why isn't it in the public domain, without copyright restrictions?

As published in The Guardian. Thanks to Charles Arthur and The Guardian for covering this material. Copyright remains with the aforementioned.

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