When Labour came to power in 1997 a big thing was made about making blacklists against Trade Unionists discriminatory and illegal.You may remember the infamous Economic League blacklist that targeted assorted trade unionists and lefties. In the last 11 years strong allegations have been put forward that there still may be a blacklist in the construction industry (http://www.socialistworker.co.uk/art.php?id=8636).
I recently found reference to a blacklist that could indirectly be used to victimise trade unionists. http://www.hicom.co.uk/BusinessSolutions/literature/nsdr_datasheet.pdf
or this here
This is very worrying. Considering that the balance of proof to dismiss an employee is practically nil, kicking out a shop steward on trumped up charges of say theft could easily place said workplace rep on a blacklist. Maybe as a threat to the 'financial security of the company'.