Recently I have been experimenting with extracting UK addresses from OSM data. Where a postcode has not been tagged, I have assigned the nearest one using the OS Opendata Codepoint centroids. The nearest postcode will quite often not be the correct one, but this is sufficiently accurate for my intended use of identifying the correct city and suburb.
Having done this, I thought it would be interesting to look at which postcode areas contain the most mapped addresses, so I made a list, which I have put on the following page in case anybody else is interested: http://wiki.openstreetmap.org/wiki/User:Will_P/UK_Addresses
The Birmingham (B) postcode contains the most addresses with 80,996 tagged, followed by Colchester (CO) with 52,257 and Nottingham (NG) with 41,313. At the other end, Llandrindod Wells (LD) and, somewhat surprisingly, Sunderland (SR) only contain 9 tagged addresses.
I have also made lists for the postcode districts and sectors within postcode areas with the most mapped addresses. It should be noted that the number of addresses within these areas varies greatly, so those areas at the top of the lists are not necessarily more complete than those further down.
Having added a lot of addresses myself, its interesting to identify other places where extensive address mapping has taken place, and to look at the different styles of mapping and tagging used.
Here are the postcode districts and sectors with the most mapped addresses -
WA7 5 - Runcorn (5384 addresses)
NG9 2 - Beeston (part) and Lenton Abbey, Nottingham (5100 addresses)
BA13 3 - Westbury, Wiltshire (4987 addresses)
CV3 5 - Coventry (Cheylesmore) (4919 addresses)
NG9 3 - Bramcote and Trowell, Nottingham (4866 addresses)
B27 7 - Acocks Green, Birmingham (4857 addresses)
B11 3 - Sparkhill, Birmingham (4549 addresses)
B76 1 - Walmley, Sutton Coldfield (4441 addresses)
CO12 4 - Harwich, Essex (4315 addresses)
CB1 3 - Cambridge (south east) (4184 addresses)
CO15 4 - Clacton-on-Sea (4078 addresses)