Confidential personal data – gleaned from sources as diverse as driving licences, medical records and store loyalty cards – is now often shared without people’s knowledge, the information commission will warn on Tuesday, in its latest salvo against what it calls the “surveillance society”.

The commission says the increasingly complex web of information sharing – involving the public and private sectors, and bodies ranging from hospitals to credit reference agencies – can make it hard for people to assert their legal rights to view information held about them.