Officials were able to retrospectively locate park-goers for 12 months using anonymised mobile phone data provided by the network operator EE via a third party.Aggregated age and gender data was also made available during the initiative. If a zone of the park contained more than 50 people at once, it was possible to “drill down” to the aggregated demographic data of visitors to that area too, creating a detailed picture of how different people used the park in previous months .
Source : Hyde Park visitors covertly tracked via mobile phone data | World news | The Guardian
