london.pm Digest, Vol 16, Issue 29

[Peter Corlett]

On Wed, Feb 21, 2007 at 12:20:31PM +0000, michael wrote:
> Postcodes in central London are much much smaller than post codes in the
> Scottish highlands. So, if the coordinates are derived form postcode data,
> you would expect that the Scottish coordinates would but much less
> accurate than the London ones...

Well, a postcode covers multiple addresses, and you need the house number to
uniquely identify a "delivery point" (or a letterbox as we normally call
them).

With a postcode only, a lookup is going to get you the co-ordinates of the
first delivery point. Thus, from the point of the other delivery points,
there is an error, but that's because it wasn't actually their address being
looked up in the first place.