Why would you do this? It’s all about building a dataset of UK postcodes, in the public domain. The current database is owned by the Post Office, is expensive to license, and cannot be used without restrictions. Anything that helps build up a free-to-use set of UK data – particularly administrative and boundary data that is not physically obvious on the ground – is a Good Thing, as the current row between Google and the OS (more, more) about derived data shows.
I work with an academic team which is a major user of such data and such restrictions on use of this kind of data limit the way geographic and demographic research in the UK can be effectively disseminated to the public. Worries about viability of some of the bright ideas in Show Us A Better Way is a case in point.