Tom Steinberg on the Task Force has drawn my attention to this very good summary of the situation with postcode data in the UK from the Spatial Miscellany.
A dataset that reliably links postcodes to all the common aggregation boundaries and to geographical coordinates remains a key element of an analysis layer for many uses of public data.
Following comments to an earlier post on this I have been pointed to the National Statistics Postcode Directory. This appears to be the ideal solution but is not freely available, I assume because it inherits chargeable IP from the Royal Mail and Ordnance Survey elements it uses.
Richard Allan, Task Force Chair