If you’re ever struggling to locate an address through the online phone directories and the customer’s sure the occupant hasn’t moved, try feeding the information into Google Maps (the address, not personal names). It’s not infallible but it’s worth a stab for the occasional eureka moment you’ll experience.
I tried this recently, with success, after a fruitless search on British Telecoms’ PhoneNet UK advanced search. It turned out that everything about the address was correct except the postcode and the name of the (small) town, which the customer had spelled wrongly. Google Maps accepted the wrong address and delivered the correct one with amended place name and post code.