Labour’s Andy Burnham has threatened to oppose the government’s draft investigatory powers bill on spying by the police and security services unless ministers release all available papers on what he called “a politically motivated show trial” from the 1970s.

The Shrewsbury 24 – including the Royle Family actor Ricky Tomlinson – were a group of activists campaigning for better pay and conditions during a 1972 builders’ strike; they were convicted of public order offences and sent to prison. The group have always protested their innocence and believe the trial was politically motivated.

The Criminal Cases Review Commission has been considering since 2012 whether there are grounds for referring the convictions to the court of appeal as potentially unsafe.

On Wednesday, documents were released to parliament that suggested police destroyed original witness statements and framed new testimony to convict the activists.But the shadow home secretary says some documents are being held back. “What possible justification can there be, 43 years on, for information about it to be withheld on national security grounds?” Burnham said. “The failure to disclose has less to do with national security and much more to do with the potential for political embarrassment.

“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.”

The documents, discovered over years spent in public archives by Eileen Turnbull, the campaign’s researcher, reveal that Robert Carr, the home secretary in Edward Heath’s Conservative government, took a personal interest in the prosecution of the men.

A new unit operating in the Foreign and Commonwealth Office was at the same time gathering evidence on allegedly subversive communist involvement in the trade unions, which it then passed to a television documentary, Red Under the Bed, which aired twice at crucial points during the trial.

Andy Burnham said Labour could oppose new spying powers unless ministers agree to publish all the Shrewsbury 24 documents. Photograph: Gareth Fuller/PA

In one secret memo, a senior official in the FCO’s information research department said the unit “had a discreet but considerable hand” in the documentary, which was presented by the former politician Woodrow Wyatt. The memo, seen by Turnbull, said Wyatt “was given a large dossier of our own background material”, including a paper on “violent picketing”.

The official said of the programme: “In our estimation [Wyatt’s documentary] was a hard-hitting, interesting and effective exposure of communist and Trotskyist techniques of industrial subversion.” Alleging violent picketing and communist infiltration of trade unions, the documentary, which included footage of the Shrewsbury defendants, was broadcast by ITV on 13 November 1973 as the prosecution closed its case, then repeated in December when the judge, Chetwynd Talbot, was summing up, according to Turnbull.

Heath then received a note from his principal private secretary inviting him to “glance through the transcript” of the programme; Heath scribbled on the memo: “We want as much of this as possible.” That encouragement from the prime minister apparently led to the formation of a new unit within the security services to gather further evidence on trade union activities.

The Shrewsbury activists, who were campaigning for better wages and conditions in the building industry, went to seven different sites on 6 September 1972. They say they alerted police – whose number grew to 80 – after an agent at the first site threatened them with a shotgun.

Tomlinson, who later found acting success in Brookside, Cracker and The Royle Family, says there was no trouble, and recalls that the police made no arrests or cautions on the day. However five months later, in February 1973, they were arrested and charged with offences including intimidation, conspiracy to intimidate and unlawful assembly; 24 men were convicted after three separate trials.

The documents unearthed by Turnbull include a page from the director of public prosecution’s file on the Shrewsbury defendants in December 1972, which said: “The home secretary is interested in this case.” On 20 September 1973, in the late stages of preparing the case, a note of a conference with Maurice Drake QC, the lead prosecution barrister, apparently made by a police officer, states: “It was mentioned that not all original handwritten statements were still in existence, some having been destroyed after a fresh statement had been obtained.

“In most cases the first statement was taken before photographs were available for witnesses and before the officers taking the statements knew what we were trying to prove.”

The Shrewsbury 24 campaign’s solicitor, Rhona Friedman, of Bindmans, who made the application to the CCRC, said the note “has the potential to be the most shocking and revelatory document detailing possible prosecutorial abuse of process that I have seen”. She added: “It suggests that the police may have gathered evidence in this case to fit a predetermined narrative and destroyed evidence which didn’t fit.”

In a Westminster Hall parliamentary debate on Wednesday, Burnham described the Shrewsbury 24 as: “The convenient scapegoats of a government campaign to undermine the trade unions; the victims of a politically motivated show trial orchestrated from Downing Street, the Home and Foreign Offices and the security services.”

Burnham called for the publication of all the documents connected to the case, some of which are still being withheld on security grounds. He argued that they disclose “misuse of powers in the way we were governed and policed in the second half of the last century”, and that the current government should be honest and transparent about these abuses, particularly if it wants Labour’s cooperation in giving greater investigatory powers to the police and expanded security measures.

Replying on behalf of the government, the policing minister, Mike Penning, said the Home Office was looking at the documents it holds and assessing whether they could be published.

“There has been a decision, not my decision ... by the cabinet secretary [Sir Jeremy Heywood] and the chancellor of the Duchy of Lancaster [Oliver Letwin] to say that what they have seen – and I think the cabinet secretary is fairly independent on these things – that there is no relevance in the documents that they have withheld to the case of the Shrewsbury 24.

“And the Cabinet Office stands by their decision, and the government stands by their decision, not to release those documents on the grounds of national security.”

Several of the 24 men convicted never found work again after being released from prison, and five have now died. Tomlinson said the convictions have done long-term damage to the men and their reputations. “We have paid a very heavy price, and after all these years we want our names cleared and for the truth to be established about what was done to us, and who was responsible.”



Letwinsaid in October that the documents covered by security considerations would not be published. “They do not relate in any way to the question of the safety of the convictions of the Shrewsbury 24, and, crucially, all of those papers have been released to and been reviewed by the Criminal Cases Review Commission.”

