The decision to drop charges against the pair has been criticised by MPs, including Commons Speaker Sir Lindsay Hoyle who said it could leave Parliament vulnerable to espionage.
Conservative MP Alicia Kearns, who previously employed Mr Cash as a parliamentary researcher, said it was “inexplicable” that the trial would have collapsed “without either ministerial or national security advisor or executive involvement”.
“I have no question that the Crown Prosecution Service made this decision independently,” she told BBC Radio 4’s Today programme earlier.
“However, it seems very clear to me that their ability to prosecute was spiked.”
“The evidential standard was met when charges were laid and something has happened, and I’m afraid it happened in the last few weeks before the trial was meant to go to court, where something changed, where the evidential standard was no longer met because something was withdrawn,” she said.
“That can only happen if a witness was withdrawn, evidence was withdrawn, or the intelligence on which an officer of the state was expecting to operate was withdrawn…
“Either ministers or senior advisors acted with [Keir] Starmer’s full knowledge, or they acted in contradiction and contempt of his wishes in a way that spiked the CPS’s ability to prosecute.”
Kearns, who has been a vocal critic of China, said she was concerned the government was “putting our national security second” because it wanted to reset relations with Beijing.
In October 2024 David Lammy became only the second foreign secretary in six years to visit China, where he said Beijing and London should “find pragmatic solutions to complex challenges”.
Since last year’s general election, Labour has sought closer trade ties with China to help boost economic growth.