Thanks - appreciate the info. I had a look at the data and there are indeed many instances where there is the same locality name spanning different postcodes, however, when you look at the reasons for their existance, then each one is actually a different physical location. In most cases this seems to be semantic although technically a different location. Examples are mainly for a large organisation to sort mail eg to differentiate say general mail, competition entry mail and perhaps parcels which are delivered to (most likely) the same building. I couldn't see any instance of a locale (if you include the delivery office and category + state) spanning multiple postcodes, although I have to admit I only scanned the data. I'll run some queries on it later and post the results, although I guess you have already done this at some point :-)
