Why do two or more addresses have the same Address Key?

Summary

An Address Key is a unique 8-digit number that the Royal Mail assigns to each address on PAF. This Address Key alone however is not always sufficient to uniquely identify an individual delivery point.

Solution

There are two reasons why duplicate Address Keys may be encountered:

1. Two or more small user delivery points with the same PAF address can have the same Address Key. Royal Mail only assigns one Address Key to each address on PAF so, for example, the two companies at 519 Etruria Road, Stoke on Trent, ST4 6HT will have the same Key.

2. The Address Key for a large user postcode can be the same as the Address Key for a small user postcode. This is valid because Address Keys for large user postcodes only have to be unique for the large user postcodes on PAF, and the Address Keys for small user postcodes only have to be unique (to address level) for the small user postcodes on PAF. For this reason, the Delivery Point type is required to distinguish between a large user and small user address with the same address key value. Examples of this in the Q4 2002 data are the large user at RH10 1UN and premise 58 at BN1 7JA.