I need to post a few letters, and I wasn’t sure exactly where the nearest postbox to my house is, so I asked Google. First of all I was rather surprised that Royal Mail don’t offer a postbox locator service themselves, this seems like a massive oversight on their part as it would be a very useful tool.
Second to that, I have discovered that the Freedom of Information act is rather neat. Some friendly folk wanted to put together a website where you could search for a postbox yourself, and lo and behold they were able to acquire a complete listing of postbox locations direct from the government on request. Furthermore, that information was made publically available (all be it in a pretty horrible PDF file) here: http://www.whatdotheyknow.com/request/location_of_every_post_box_that
Thankfully someone then took that and converted it into a much nicer format, which can be found and browsed easily here: http://edwardbetts.com/postboxes/
Since the information is there now, I suspect someone will take the time to make a search by location database available in the near future. The internet is nifty!