&gt; <i>This was mostly construction industry keeping a list of union members who were engaged in legal union activity, often around safety. (UK construction at the time was pretty risky, one of the most dangerous industries in the country.)</i><p>There was also (AFAIR) blacklists of suspects IRA terrorists, also in the construction industry. (Many Irish emmigrants to the UK were poor and worked in manual labour jobs like construction.)<p>Another example of data protection issues and &quot;terrorists&quot;