SECRET documents implicating a former Tory prime minister, spooks and senior cops in colluding to secure convictions against the Shrewsbury Pickets were sensationally revealed in Parliament yesterday.

The government has cited national security concerns as the reason it cannot release classified documents that could help overturn convictions against 24 builders, including jailed pair Ricky Tomlinson and Des Warren.

But shadow home secretary Andy Burnham blew the case wide open by exposing previously unseen documents in a parliamentary debate on the historic injustice.

The explosive contents could help clear the names of the 24, nine of whom have since died, over four decades after the 1972 strike over pay and safety.

Mr Burnham said: “The documents I have revealed can only lead us to one conclusion — the Shrewsbury 24 were the convenient scapegoats of a government campaign to undermine the trade unions and the victims of a politically orchestrated show trial.”

They include a memo, marked “secret,” which proves the security services helped make the infamous Reds Under the Bed TV documentary.

The programme, which linked the workers to supposed communist infiltration of the Labour Party, was shown on the very night that the prosecution concluded their case against the pickets.

The memo was sent to a senior Foreign and Commonwealth (FCO) official by the head of the Information Research Department, which Mr Burnham described as a “covert propaganda unit” operating within the department.

It said: “We had a discreet but considerable hand in this programme. Mr Wyatt was given a large dossier of our own background material. It is clear from internal evidence in the programme that he drew extensively on this.”

Another memo reveals that knowledge of this smear campaign went all the way to the top.

After the programme was shown, then PM Edward Heath was sent a transcript of Reds Under the Bed.

Mr Heath replied: “We want as much of this as possible.”

A further note from the PM’s parliamentary private secretary alludes to a “new unit” which Mr Heath hoped was “in being and actively producing.”

“There we have it,” Mr Burnham told stunned MPs.

“The security services were helping to make a TV programme that was not just nakedly political in its aims of damaging the Labour Party. But in the case of the Shrewsbury 24, a programme that was prejudicial to their trial.

“The government were complicit in making that happen.”

Other documents unearthed by the Shrewsbury 24 Campaign reveal how then Tory home secretary Robert Carr directed police evidence-gathering.

A note from a meeting between chief constables and the prosecutors shows some inconvenient witness statements were destroyed.

It said some were “destroyed after a fresh statement had been obtained” because the first statement was taken “before officers taking the statements knew what we were trying to prove.”

That could be connected to a letter from the attorney general to Carr in January 1973 advising him that there was “no evidence of violence of damage to property” at the pickets.

Labour MP Ian Lavery, chair of the party’s trade union group, said it proved the case was a “miscarriage of justice organised deliberately by the state.”

Even Policing Minister Mike Penning, who refused to reopen the case in October, was stunned by the evidence.

He congratulated the campaign for unearthing the documents, but bought time by saying:” I don’t make instant judgements.”

Builders’ union Ucatt acting general secretary Brian Rye said: “In the 21st century — if this is truly a democratic country — its citizens are entitled to know why innocent men were sent to prison more than 40 years ago, under a trumped up, 19th-century law.”