Campaigners have welcomed the London Assembly's decision on Wednesday to investigate claims of blacklisting at on the city's Crossrail project.
It passed Labour AM John Biggs's motion which noted that the "links between the shameful and unlawful practice of blacklisting and Crossrail's industrial relations manager Ron Barron risk tarnishing the integrity of this taxpayer-funded project."
It was alleged in December that at his previous job at building firm CB&I Mr Barron used a blacklist of trade union members compiled by the Consulting Association, which was raided by Britain's data watchdog in 2009.
Evidence given at an employment tribunal showed that Mr Barron cross-checked job applicants against the list, which he helped compile.
The tribunal found that he introduced the use of the blacklist and referred to it more than 900 times in 2007 alone.
A Crossrail spokesperson said Mr Barron had been off the project since November and claimed that there was no evidence of blacklisting.
But Consulting Association boss Ian Kerr told Parliament's Scottish affairs committee in November that an "awful lot of discussion took place at Consulting Association meetings about the Crossrail project."
Last year unions reacted with fury when 28 workers were removed from the Crossrail project after reps raised safety concerns, which the assembly's motion notes.
It calls on London Mayor Boris Johnson to "disassociate himself from such practices and emphasise that every employee must be protected in raising health and safety concerns without fear of reprisals."