With the recent takedown of the postcode geocoding API provided by Ernest Marples Ltd, there has been discussion of other ways to get hold of postcode data without paying prohibitive licence fees to Royal Mail. One solution is to collect the data from scratch, without using existing sources that are derived from the Royal Mail licensed database. This has at least some chance of avoiding the infringement of Royal Mail’s intellectual property rights.

There are several such projects already in existence. The oldest is Free The Postcode which invites visitors to collect the location of a postcode by visiting a location and recording the latitude and longitude of its postcode using a GPS. There are simple mobile applications to automate this process for the iPhone and other GPS-enabled devices.

If you don’t have a GPS, it might be worth heading over to the New Popular Edition Maps site to explore some out of copyright Ordnance Survey maps. This project collects data by allowing people to pinpoint a postcode on these maps. These data are less accurate because of the way the old maps are presented, but you don’t need a GPS to contribute, and the site has managed to collect an impressive number of postcodes this way.

Another project that has recently popped up is the Open Postcode DataBase, which is more ambitious, aiming to capture street and town names as well as postcode data.

Lastly, the Locating Postboxes site is using information collected, ironically, from an FOI request to the Royal mail concerning the location of these postboxes, and asks users to pinpoint the postboxes on a map.

These projects are placing their results into the public domain. At the moment they only provide data equivalent to a small fraction of those that the Royal Mail makes available (NPEMaps has around 45,000 postcodes, whereas Royal Mail will give you around 1.8 million). For many applications, however, where only area/district accuracy is required, they are already useful sources. Free The Postcode and NPEmaps allow download of the complete data, for individual postcodes, and averaged over postcode prefixes and sectors, and NPEmaps offers a basic geocoding API suitable for low traffic sites.

I am currently involved in both Free The Postcode and the New Popular Edition maps, and we’re interested in making these data sets more accurate and readily available. We would welcome offers of help from developers who are interested in making this happen, and of course more contributions of data!

This post is Copyright 2009 by Dominic Hargreaves, and is licensed under the Creative Commons Attribution-Share Alike 2.0 UK: England & Wales licence