Vulnerabilities in the use of similarity tables in combination with pseudonymisation to preserve data privacy in the UK Office for National Statistics' Privacy-Preserving Record Linkage

In the course of a survey of privacy-preserving record linkage, we reviewed the approach taken by the UK Office for National Statistics (ONS) as described in their series of reports “Beyond 2011”. Our review identifies a number of matters of concern. Some of the issues discovered are sufficiently severe to present a risk to privacy.