Mr Collins submitted his first witness statement in December 2023, after which prosecutors decided they had enough evidence to charge Mr Cash and Mr Berry under the Official Secrets Act 1911.
However, Mr Parkinson said a ruling in a separate court case in 2024 changed the requirements of what evidence would be needed and so prosecutors asked Mr Collins to provide further witness statements, in the hope he would label China a “threat to national security”.
In two further statements, Mr Collins detailed threats posed by China in cyberspace and to the UK’s democratic institutions but avoided labelling the country “a threat to national security”.
The collapse of the case triggered a political row over who was to blame. The Conservatives have accused the Labour government of allowing the case to fail because it wanted to foster better relations with Beijing.
However, the government said ministers had no role in providing evidence for the case and Mr Collins was giving evidence based on what Conservative government policy had been at the time.
Mr Collins had a meeting with the top civil servant, Sir Chris Wormald, and National Security Adviser Jonathan Powell on 1 September, shortly before the case collapsed.
Sir Chris told the committee that the meeting had been held to discuss how to handle “different scenarios” of the UK-China relationship.
Mr Collins added that there had been “at least four lawyers in the room who ensured that there was no discussion about the evidence” in the case.
The Conservatives will hold a vote in Parliament on Tuesday demanding the government releases various documents, including minutes of meetings where the case was discussed by civil servants or ministers.
On Wednesday, the committee will hear evidence from Attorney General Lord Hermer and senior minister Darren Jones.