Geo-Coding the UK

I’m currently building a web site that will involve plotting the positions of buildings onto maps. I’m going to be using Google maps for that. Unfortunately, the data that I need to plot is a list of postcodes and as far as I can see, the best way to plot stuff on a Google map is by using its latitude and longitude.

So I needed a way to convert UK postcodes to lat/long. The frustrating part is that I know that the BBC has an application that does that (and many, many other things) and that they have been planning to release it as part of Backstage for some time but that licensing issues have been preventing that from happening.

And licensing is at the heart of the problems faced by people trying to write geographical systems for the UK. Most of the truely useful data is owned by commercial organisations who want to make money out of it. Postcode information is owned by the Post Office and a lot of other data is owned by the Ordnance Survey. And the licenses for this data are expensive enough to prevent most people from using it. This is the basis of the Guardian‘s Free Our Data campaign.

At this point, I should point out a couple of projects that are trying to address this problem by building a free database of postcodes – Free The Postcode and New Popular Edition Maps. I’d urge you to visit both of these sites and tell them about any postcodes that you know.

Unfortunately, the coverage of both of these projects was too patchy to be of any use to me. But then someone pointed me at and all my problems were solved. This site converts between many UK geographical coordinate systems – including converting postcodes to lat/long. And it has a nice web services API which made it simple to write a program to grab the hundred or so values that I wanted.

All in all, a successful afternoon’s work.

Oh, and whilst experimenting with Google maps, I built this – places I have lived in London


  1. Doesn’t the new Google Maps API include geo-coding? I think this is a recent addition, before you were just able to use coordinates. I know that doesn’t seem to have problems with addresses like “nw5 1lb, uk”.

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