MI5 chief ‘frustrated’ over collapse of China spy case

Chinese state operatives present a daily national security threat to the UK, the head of MI5 Sir Ken McCallum has said.

In a speech, he said MI5 had intervened operationally to disrupt Chinese activity of national security concern in the past week.

Addressing a row over the collapse of a case involving alleged spying on behalf of China in the UK, Sir Ken said the alleged activity was disrupted by MI5 and that it was “frustrating when prosecutions fall through”.

The government and the Crown Prosecution Service (CPS) are facing questions over the collapse of the case.

The CPS dropped the case last month after deciding the evidence did not show China was a threat to national security.

But witness statements from the UK’s deputy national security adviser Matthew Collins – published late on Wednesday – are clear that the Chinese are carrying out spying operations against the UK, raising questions for the government and the CPS about why the prosecutions did not go ahead.

In the documents, he said China was carrying out “large scale espionage” against the UK and was “the biggest state-based threat to the country’s economic security”.

Sir Ken described Mr Collins as a “man of high integrity and a professional of considerable quality”.

In his speech, Sir Ken said “Chinese state actors” presented a threat to UK national security but added that the “overall balance” of the UK’s relationship with China was “a matter for the government”.

“When it comes to China, the UK needs to defend itself resolutely against threats and seize the opportunities that demonstrably serve our nation,” he said.

The Conservatives have accused the government of allowing the spy case to collapse to avoid jeopardising economic relations with China.

Downing Street said it would have been “absurd” for the PM to step in last month after being told the case was going to collapse, stressing it was a “criminal matter” for the CPS to handle independently.

In a letter to the prime minister, Conservative leader Kemi Badenoch said the events leave “a strong impression that your government undermined Britain’s national security because you are too weak to do anything other appease China”.

In his reply, Sir Keir argued that the prosecution’s case relied on the then Conservative government’s policy towards China at the time of the alleged offences, between 2021 and 2023.

“In other words, the prosecution’s case required demonstrating that the position of the then Conservative government was that China was an enemy of the United Kingdom,” he said, and it was “plainly wrong” to suggest that had been the case.

The head of the CPS Stephen Parkinson is also in the firing line, with MPs suggesting there was sufficient evidence to put the case before a jury.

He is reported to have told senior MPs on Wednesday that the evidence was “5%” short of what would have been required to stand a chance of getting a conviction.

The Conservatives have written to the CPS to ask what evidence it had wanted the government to provide.

And the chairs of four parliamentary committees have written to Mr Parkinson asking for “a fuller explanation for the dropping of charges”.

Labour MP Emily Thornberry, who chairs the foreign affairs committee, told the BBC’s World at One: “I can’t see that the jury would have had any problem deciding that China was a threat.

“I really don’t understand why they [the CPS] were being so pusillanimous about it.”

Another signatory, Labour MP Matt Western, has said the Joint Committee on the National Security Strategy is launching a formal inquiry into the case.

In the first witness statement, sent in December 2023, Mr Collins outlines the case against former parliamentary researcher Christopher Cash, 30, and academic Christopher Berry, 33.

The pair are accused of collaborating with a Chinese Communist Party leader who was deputy director of the Central National Security Commission, chaired by President Xi Jinping.

In one message, Mr Cash is alleged to have told Mr Berry: “You’re in spy territory now.”

Both men deny any wrongdoing.

The second witness statement, written by Mr Collins in February 2025, after Labour had taken power, said China’s spying threatened “the UK’s economic prosperity and resilience”.

A third witness statement published in August this year restated the UK’s view of the challenge posed by China.

But the two statements submitted under Labour made clear the government was “committed to pursuing a positive economic relationship with China”.

China’s foreign ministry spokesperson Lin Jian said: “China’s position is very clear: we firmly oppose peddling China spy narratives and vilifying China.”

In a Commons debate, former Security Minister Tom Tugendhat, for whom Mr Cash was a parliamentary researcher, accused the government of being obsessed with following the correct process, rather than doing everything it could “to make sure the prosecution works”.

“Who the hell’s side are you on?” he asked the government.

In a statement released on Wednesday evening, Mr Cash said he had been placed in an “impossible situation” because he had not “had the daylight of a public trial to show my innocence”.

He added: “The statements that have been made public are completely devoid of the context that would have been given at trial.”

In a separate statement, Mr Berry said: “I pleaded not guilty to the charge, and I have been acquitted.

“My reports were provided to a Chinese company which I believed had clients wishing to develop trading links with the UK.

“Those reports contained no classified information… and drew on information freely in the public domain, together with political conjecture, much of which proved to be inaccurate.

“I do not accept that, in so doing, I was providing information to the Chinese Intelligence services.”

The third witness statement includes the words “we will co-operate where we can, compete where we need to, and challenge where we must”.

Conservative MP Alicia Kearns, who also previously employed Mr Cash as a parliamentary researcher, noted that the phrase was “a direct lift” from Labour’s manifesto.

“It’s very hard to believe there was no political interference,” she added.

“In my view, the Crown Prosecution Service should have proceeded with this.

“The case law shows it’s for a jury to decide if China is or could be a threat to our country.”

BBC News understands that Mr Collins assumed he had given enough evidence for the prosecution to continue when he submitted his third witness statement in August 2025.

A government source pointed to comments made by him where he described “the increasing Chinese espionage threat posed to the UK” as an example of why he believed he had said enough to satisfy the CPS’s threshold for prosecution.

It is also understood that the CPS contacted Mr Collins after his first witness statement to ask for further clarification on the threat posed by China, but that they were not explicitly clear what the official would need to say in subsequent statements, in order to meet the CPS’s threshold.

The director of public prosecutions has said there was sufficient evidence when charges were originally brought but a precedent set by another spying case earlier this year meant China would need to have been labelled a “threat to national security” at the time of the alleged offences.

Liberal Democrat foreign affairs spokesperson Calum Miller said the witness statements raised “yet more unanswered questions”, adding: “We clearly need a statutory public inquiry to get to the bottom of this whole fiasco.”