At its heart this is not an Excel question. First thing
you should do is work this through "by hand" - how can
you achieve this? From that you should get something you
can then implement on a spreadsheet.

Dont know if your postcodes are "meaningful" eg you can
imply something geographically from them. I would think
to do this you wouild need to be able to refer to some
coordinate system so you can deduce & test seperation.


ttfn benm