Labour could oppose new spying powers unless ministers agree to publish documents relating to the "political motivated show-trial" of the so-called Shrewsbury 24 and other past injustices, shadow home secretary Andy Burnham will suggest today.
Mr Burnham will present to Parliament a new dossier of evidence on the jailing of the pickets more than 40 years ago and call on the Government to release papers it has withheld for national security reasons.
He claims the new files show the "highest levels" of political involvement in the decision to bring charges against the builders - whose number included Royle Family actor Ricky Tomlinson - the manipulation of witnesses, and attempts to influence the judge and trial jury.
Failure to release all documents about the case could jeopardise any Labour support for the Government's Draft Investigatory Powers Bill as ministers need to "build trust", the shadow home secretary will indicate.
The Bill will still be expected to pass the Commons but with Tory MPs such as David Davis raising concerns about civil liberties, a lack of Labour support could make its progress more difficult.
In October, Cabinet Minister Oliver Letwin retained the Shrewsbury 24 papers for reasons of national security and said the decision would not be reviewed until 2021.
In a Westminster Hall debate on the issue, Mr Burnham will say: "The Government is asking for Labour's support to give the police and security services more expansive investigatory powers.
"I have said that I am prepared to consider the case for that.
"But, if the Government wants our support, it needs to do something in return to build trust. It should hold up a mirror to the past and be honest about times when powers have been misused.
"By doing that, we will have honesty and transparency and be able to build in safeguards going forward, learning from this country's past mistakes."
Presenting his dossier of evidence, Mr Burnham will accuse Ted Heath's government and the security services of underhand involvement in the industrial dispute.
The Shrewsbury 24, who were arrested five months after the 1972 building workers' strike and charged under the 1875 Conspiracy Act, with six sent to prison, were scapegoats in a state "propaganda war" against trade unions, he will say.
In a Westminster Hall debate on the issue on Wednesday, Mr Burnham will say: "This memo trail at the very top of the Government reveals the shocking extent to which the offices of the state were waging a propaganda war against the trade union movement.
"The Shrewsbury 24 were the convenient scapegoats of a Government campaign to undermine the unions; the victims of a politically-motivated show trial orchestrated from Downing Street, the Home and Foreign Offices and the security services.
"What possible justification can there be, 43 years on, for information about it to be withheld on national security grounds? The failure to disclose has less to do with national security and much more to do with the potential for political embarrassment."
Referencing 12 separate documents, Mr Burnham will claim his files show that former prime minister Mr Heath was assured by the then-home secretary that he was taking a "close personal interest" in the Shrewsbury 24 case - with the pickets arrested and charged days later.
This overturned the view of the attorney general, director of public prosecutions and Treasury lawyers that the case did not warrant prosecution as there was no evidence of violence, he will say.
The papers also show the police notifying prosecution lawyers that original handwritten witness statements were destroyed and rewritten once officers "knew what we were trying to prove".
Mr Burnham will claim a television documentary called Red Under the Bed was aired during the trial with the "discreet" yet "considerable" assistance of a major state department and the security services, conflating footage of the accused with claims of communist infiltration of the strike.
The documentary was watched by the trial judge, aired the day after the prosecution finished its case and Mr Heath wrote in a private note: "We want as much of this as possible", he will tell MPs.
Finally, the building employers' federation compiled a document for the home secretary on intimidation with views to tightening up strike laws, and accused the pickets of violence and "mobster" tactics.
Mr Burnham will say the case resembles the cover-up of the Hillsborough disaster, a subject on which he has campaigned, and South Yorkshire Police's handling of violence at Orgreave coking plant during the 1984 miners' strike.