Free Simple UK Geocoding Searches - via Google
Mapperz is asked a lot about UK Geocoding and Address Geocoding.
The Google Maps API will Geocode Addresses but due to "Contractual Reasons" they are not allowed to provide it for the United Kingdom. But Google does have this information available to you and yes you can retrieve it with simple google searches via Google Maps.
Here is a very basic request
using Google Maps (UK Version)
An address Search term
"10 Downing Street, London"
Gives you this result
Click "Link to this Page" will give you a long url
ignore the first Latitude and Longitude and take the second pair.
you can also add zoom levels
will zoom in to street level.
This can be also exported to a kml and be viewed in Google Earth.
This will create a .kml and ask you to open it or save it.
If you save it - this can be renamed .xml for use in other applications etc.
If your a programmer you can batch this up to make an address database free of charge.
For Real Programmers this looks to be an excellent source for on the fly geocoding
geopy includes geocoder classes for MediaWiki (with the GIS extension), Semantic MediaWiki, the Google geocoder, the Yahoo! geocoder, geocoder.us, Virtual Earth, and GeoNames.