[gbuk2013]

From my anecdotal experience of 1 attempt of writing to the ICO it was 100% effective: several months later I received a polite response with a history of communication between ICO and the organisation I complained about, where the latter had to justify what they were doing. This was a sports organisation that originally announced that they would be putting DOB of the athletes on their public profiles, but ultimately was just the age (because there are age bands in competitions) maybe as a result of my complaint - who knows?