I am a fluent PHP/MYSQL programmer. I need a UK postcode location
system for a PHP application that I am building. Basically I want to
tag items in my DB with postcodes, and thus find all the items within
a 10, 20, etc mile radius of a website users postcode.

I'd like a review (pro's, cons) & costings of at least 4 different
options available, ideally covering an opensource option, an API
option and a Royal Mail option.

Hi,

I work for a major Building Society. We researched Post Code
validation/search providers to use with our systems about 7 years ago,
but I doubt much has changed, given the limited nature of the market.
The two major players were Quick Address Systems (QAS - now part of
Experian)and GB Group plc. They provide a variety of solutions from a
simple PAF search engine (with easy to use API's) to more complex
tools utilising Ordnance Survey referencing, the electoral register
and more. We found little to differentiate the products as
demonstrated, but opted for QAS on the basis of advice from
independant data cleansing firms and a good deal on the price!

Thanks for the comment dude!

But I honestly think a LOT has changed in 7 years! 7 years is a long
time on the internet!