retention retention retention retention ICO website retention retention Principle 5 – Retaining personal data retention Retention retention fifth data protection principle Not kept longer than necessary up to six years retention fifth data protection principle on ‘retention’ up to six years Retention no longer than necessary retention principal 5 of the Data Protection Act Not kept longer than necessary It stipulates It stipulates retention retention retention up to six years retention up to six years retention retention retention processing of personal data, ICO