The UK Office of National Statistics announced they have released some OpenData under the Open Government Licence. This is all based around GB postcodes, excluding Northern Ireland.
Edit: Postcodes for Northern Ireland (BT codes) are included. They are based on the Irish National Grid and need to be transformed to the projection OSM uses with the EPSG geodetic parameter EPSG:29902; OSGB needs EPSG: 27700.
I downloaded the data as a CSV and checked what the format looked like. A quick Python script using the proj4 extension for Python and the OSGB northings and eastings turned into longitude and latitude. Checking for expired postcodes and missing northings and eastings and I had a set of data in the same format as my existing CodePoint Open data. I reused the tile rendering process that I'd used with the CodePoint Data. So now I have GB postcode tiles based on Open Government Licenced data to use as an overlay on JOSM and Potlatch2. They work as an overlay on Leaflet or OpenLayer too. There's some information here, including an overlay. So now I have GB postcode tiles based on Open Government Licence data to use.
The work I put in to get permission to use the CodePoint Open data from Royal Mail seems to have been ignored by the Licence Working Group. I passed the written permission on to them so they could remove the statement excluding the CodePoint Open data on the OS OpenData page. When I removed the statement it was quickly reverted by the guy who caused the phoney fuss about the OS OpenData licence in the first place. Rather than start an edit war I asked the LWG to make the change, but that seems to have been too difficult for them to do, as does answering my emails.
Still, now UK postcodes are available and I hope people will find them useful and uncontroversial.