The blacklisting scandal exploded in the faces of Britain's secret police today.
Labour MPs demanded a full-scale investigation into damning new evidence that the police and security services have been deeply involved in blacklisting of innocent workers.
The revelations electrified a Labour-led parliamentary debate focusing on thousands of construction workers and green activists who were targeted by the disgraced Consulting Association (CA), which closed down in 2009.
Former CA chief blacklister, the deceased Ian Kerr, spoke from beyond the grave when the Times published an interview with him which had previously been held back for legal reasons.
Mr Kerr confessed that the CA had close links with police and security services, and that there was a two-way exchange of information.
He recalled a 2008 meeting where eight construction industry bosses were addressed by a "key officer" from the National Extremism Tactical Co-ordinating Unit, set up by the police to counter "extremist groups."
The police unit was seeking a channel to inform construction companies about the information they were collecting.
In return, the police asked companies to give them information about potential troublemakers.
Furious Labour MP Ian Lavery tackled the Prime Minister directly at question time, demanding an investigation into secret police activities.
The PM told Mr Lavery that blacklisting was "a completely unacceptable practice," but he failed to comment on the police issue.
Mr Cameron also declared complacently: "We have seen no evidence that the blacklisting regulations introduced are not doing their job, and the company responsible was shut down in 2009."
Angry Labour backbenchers also pounced on Business Secretary Vince Cable and demanded a Leveson-type inquiry into the role of the police and secret service.
There were gasps as Mr Cable suggested meekly that the allegations should be referred to the Police Complaints Commission or to the tame tribunal which investigates complaints against MI5.
Shadow business secretary Chuka Umunna leapt to the despatch box to protest: "I am genuinely flabbergasted by the Secretary of State's response."
Demanding a full-scale inquiry into the "shameful" blacklisting scandal, Mr Umunna said any investigation must include the role of the police and security services.
Mr Umunna said he had seen files seized from the CA by the Information Commissioner's Office and some contained information which it seemed "improbable" was only gathered by construction companies.
"For example, in-depth analysis of an individual's home circumstances and what his neighbours thought about him features on one file."
Mr Umunna admitted there was a case for strengthening anti-blacklisting regulations which were introduced in 2010 by the Labour government.
Mr Cable provoked Labour MPs by claiming that he could not launch an investigation until he had been given evidence on what "was" or "is."
He said: "We have got to have evidence that something is happening."
Former miner David Hamilton MP told how he had been blacklisted for two-and-a-half years and his wife was also unable to get a job until she changed her address to his mother's address.
Mr Hamilton added: "No doubt I was on the list because I was a communist at the time."
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