From: Fred Smith 
Newsgroups: uk.finance
Subject: Re: Bank Of Scotland Botched Disguised Mail
Date: Mon, 26 Sep 2005 11:44:01 +0100

Derek ^ wrote:

> IIRC we run a paralel US style Zip code system. Which is why you see
> (or used to) strangely familiar long strings of numbers in the
> addresses on envelopes which have been posted to you from mass
> mailings. I don't know if that's still happening, nothing on the Royal
> Mail website about it.

I think you might be referring to Mailsort - if so there is plenty of 
information about the service on the website.  It doesn't replace the 
postcode though.