The origins of the existing UK Postcode go back as far as the middle of the nineteenth century and arose from the rapid growth of London in the earlier years of that century. So rapid was this that the then Post Office could no longer regard the city as a single town from the viewpoint of sorting mail. Thus the division of London into Postal Districts in 1857-8 effectively divided the capital into smaller and semi-independent postal towns. Sir Rowland Hill, the designer of the first stamp and the man who introduced the uniform postal rate for the whole country, carved up London into eight such Districts.
Some interesting stuff here, courtesy of our very own Ministry of Defence, with regard to the UK’s nuclear weapons. You’d think some/most (maybe all?) of this raw data would be much more hush-hush. But hey, what’s the point in having warheads if you don’t tell anyone (everyone) you’ve got them?