We used to get people coming in to the station all the time to complain about the driving of others. Usually they were blue rinse grandma's that had been overtaken quite legitimately whilst doing 25 mph in a 60 limit. They made a report and were happy, we threw the report in the shredder and were also happy. These people usually had no description of the driver, make, model, colour or direction of travel of the "offending" vehicle. Quite what the Police were expected to do is anyones guess