You can also see UPRNs for buildings that no longer exist, so you have to be careful to avoid these. For example, in Peacehaven, plenty of single houses on a plot have been demolished and two put in its place. The UPRN tool may well show 3 UPRNs in this case, so I check the centroids to determine the correct UPRN. In some cases, the centroid seems a little off, but then I find that the outline needs adjusting from the aerial imagery; someone might have just plonked a rectangle there in the first place.