https://www.techworld.com/security/privacy-concerns-raised-by-covid-19-symptom-checking-app-3785292/

The app, developed by the NHS's innovation wing NHSX, will focus on tracing symptoms rather than diagnosis. It is understood that data will be stored in a central database and will require Bluetooth features to be switched on constantly to be effective – putting unique device IDs at risk. Soon after the announcement, The Guardian reported on a classified draft government memo that would give ministers the power to 'de-anonymise' users.