I'm really annoyed about this issue. What the f*ck gives employers the right to organise against employees in the form of blacklists? This is a political issue and the companies involved in this should be held up and targetted in the same way unions are held up and targetted by the Tories , today and in the last 30 years, as to interfering with the political process.
The link here provides detail of the culprits. This practice is absolutely outrageous and I find it astounding that Labour promised to deal with the blacklisting scandal pre 1997 election but have done f*ck all about it.