The documents, released under freedom of information laws to BFBS, show that concerns about potential control malfunctions and wider airworthiness issues were raised by experienced RAF voices after the crash, including by test pilots and technical experts, while officials dug deep to continue to blame the two Special Forces pilots.

The files are among those released by the MoD in a tranche of FOI documents.

The Chinook Justice Campaign’s legal team has complained about several of the files and sought restrictions on further publication, because they contain personal and sensitive data related to the families which has been unlawfully made public.

However, the documents also reveal internal correspondence which highlights a determination within the Ministry of Defence at the time to “close off” further discussion of those safety issues and reinforce the conclusion of pilot negligence.

In one document, Air Marshal Sir William Wratten outlines plans to respond to emerging alternative theories in a way designed to shut down further debate, while other papers show sustained efforts to rebut or dismiss concerns about possible technical faults.

In response to an article in Aerospace International questioning the MoD’s version of events, Sir William states that he was attempting to “close off further correspondence” by “anyone who holds an alternative view” to pilot negligence.

Sir William, along with his colleague Sir John Day overruled the official RAF Board of Inquiry in order to blame the pilots for gross negligence, a decision which contravened the RAF’s own rules.

With the 32nd anniversary of the crash looming, families say the documents demonstrate that the Ministry of Defence was not engaged in an open search for the truth at the time but was instead focused on defending an unjust and unevidenced position.

Days before the crash, the Ministry of Defence’s own test pilots had refused to fly their own Chinook Mk2 on safety grounds.

The latest files raise questions about whether all relevant evidence was made available to previous inquiries, including the fatal accident inquiry at Paisley Sheriff Court in Scotland.

The Chinook Justice Campaign is now calling for the case to be treated as one of the first tests of the proposed Hillsborough Law, which – once on the statute books - is intended to enforce a legal duty of candour on public authorities.

Mark Stephens CBE, from Howard Kennedy LLP, solicitor for the families, said: “These are documents the public was never meant to see – and they change everything. They show not a search for truth, but a determination to suppress it. Without them, the public has been asked to accept a version of events that was neither true nor properly tested.

“These documents lay bare a systemic failure of candour. They go to the heart of why the Hillsborough Law is needed and show that senior officials cannot be allowed to decide whether a Duty of Candour should apply or not.

“It’s a prime example of why the MoD and other security agencies must not be excluded from the uncomfortable facts, and avoid scrutiny.”

Elkan Abrahamson, Director at Hillsborough Law Now and Head of Major Inquiries at Broudie Jackson Canter Solicitors, added: “Hillsborough Law – the Public Office (Accountability) Bill – is currently unable to proceed to the 3rd reading and report stage, as the Security Services, including Ministry of Defence, Counter Terrorism Police and the National Crime Agency, are insisting on being excluded from the provisions applying to everyone else.”