True enough, and our cities are quite a mess in places as well, (witness here Boston,) but check *this* out, though it's only in one county...When you build or expand an apartment complex, part of your zoning approval / permitting is that you send a packet to the first - due fire stations (in our county, fire and ambulance are a joint service,) with an updated box map, and a few copies of keys to any gates, etc. Even the addition and alteration of numbers can be handled if you do them sequential-but-not-immediately-so (e.g. using the property tax map parcels to space them out, so that neighboring suburuban houses might be, e.g. 241 and 247.) That will give you room for concievable additions / deletions. But what it seems you're saying is that generally, in London, a given address *will* in general have a street number, but that people just don't use it? (And that the places without are in communities where, generally, people would know what it was?) In that case, perhaps just the improved signage (and dispatching by street number) could be a help...