The Guardian has an interesting story about postcodes in the UK:

Nearly everyone has a postal address and most householders assume they “own” it. Unlike in France, say, no law stops us removing our number and calling our home what we like. But as usual with cases highlighted by Guardian Technology’s Free our Data campaign, the truth is not so simple.

During the past seven years, disagreement between different state bodies and state-owned companies over who owns intellectual property has blocked the creation of a definitive national list of addresses. As a result, says geographer and local councillor Robert Barr, emergency responses get sent to the wrong place, council tax goes uncollected and government plans are put in jeopardy.

And apparently the postal codes are, well, encoded:

the postcode file has big gaps. According to Barr, it holds only 60% of buildings in England – the Royal Mail is not interested in structures such as churches, which do not receive mail. Because of the purpose for which they were set up, postcodes may bear little relevance to reality – the initial component, the “post town”, relates to the nearest sorting office rather than the nearest town.