CALLS for a public inquiry into construction industry blacklisting reached fever pitch yesterday after the Met finally admitted it had passed information to key blacklisting organisations.

After years of denials, Deputy Assistant Commissioner Richard Martin finally confessed to the collusion in a response to a complaint to the Independent Police Complaints Commission by the Blacklist Support Group.

The 40-year construction blacklist, organised by transnational corporations like Robert McAlpine and Balfour Beatty through the Economic League and The Consulting Association, kept secret files on more than 3,200 trade unionists, often just for raising on-site safety concerns.

Mr Martin’s letter states that the allegation “police, including Special Branches, supplied information that appeared on the blacklist, funded by the country’s major construction firms, The Consulting Association and/or other agencies” had been “proven.”

It adds that “sections of the policing community throughout the UK had both overt and covert contact with external organisations, including the Economic League.”

Mr Martin also admitted that internal investigations on undercover policing had found an “improper flow of information from Special Branch to external organisations.”

But, despite police collusion being proven, no action will be taken against any police officer.

The complaint was made in 2012, but the response was only received last week. Mr Martin explained that the report was concluded in February 2016 but had been “marked for the MPS Commissioner only, due to its sensitivity.”

Blacklist Support Group secretary Dave Smith said: “Six years we’ve waited! The report has sat on the commissioner’s desk for the past two years!

“When we first talked about police collusion in blacklisting, people thought we were conspiracy theorists. With this admission from the Met Police, our quest for the truth has been vindicated.”

He added: “If it’s happening in construction, the very same thing will be happening in other sectors.”

Shadow chancellor John McDonnell, who was the first MP to raise the issue of possible police collusion, commented: “It is now abundantly clear that various arms of the state, including the police, colluded in the blacklisting process.

“This is one of the hidden scandals of the abuse of civil liberties in our country that needs to be recognised fully and addressed. The people involved need to be brought to book.”