China obtained “vast amounts” of classified government information over a period of many years by compromising a network used to transfer data across Whitehall.
Dominic Cummings, who served as a senior adviser to Boris Johnson, said that he and the then prime minister were informed about the breach in 2020 but that there had subsequently been a cover-up.
He said he was warned at the time that disclosing some specific details of the breach would be a criminal offence. He claimed that the breach included some “Strap” material, which is the government term for the highest level of classified information.
The breach, which was confirmed by two other senior Whitehall sources, was said to have been connected to a Chinese-owned company involved in Britain’s critical national infrastructure. Tom Tugendhat, a former Tory security minister, supported Cummings’s account.
Cummings said that he and Johnson were informed of the breach in the “bunker” of No 10 — a reference to the secure room in Downing Street.
He told The Times: “The cabinet secretary said, ‘We have to explain something; there’s been a serious problem’, and he talked through what this was.
“And it was so bizarre that, not just Boris, a few people in the room were looking around like this — ‘Am I somehow misunderstanding what he’s saying? Because it sounds f***ing crazy’.”
He added: “What I’m saying is that some Strap stuff was compromised and vast amounts of data classified as extremely secret and extremely dangerous for any foreign entity to control was compromised.
“Material from intelligence services. Material from the National Security Secretariat in the Cabinet Office. Things the government has to keep secret. If they’re not secret, then there are very, very serious implications for it.”
He said he would be willing to share what he knew about the data breach with MPs and claimed that the most senior officials in Whitehall had covered it up.
Cummings declined to say how the system had been breached. “If the MPs want to finally have an inquiry about it, I’d be happy to talk about it,” he said. “And many people know that what I’m saying is true and many people will back it up.
“And many people know that after the PM was notified about this in 2020, officials from the Cabinet Office then went round telling everybody in the meeting that it was illegal for them to discuss this with the media.”
The involvement of a Chinese-owned company in the breach was first reported by The Spectator.
Tugendhat, who served as security minister from 2022 to 2024, said: “I don’t want to go into the details, but the gist of what Dominic Cummings has put out is correct.”
One senior Whitehall source confirmed that at the time the government had evidence that sensitive government information was being transferred to China.
They added that the information had been encrypted but there were concerns that this could still have been accessed by the Chinese. “It was something we were quite worried about for a while,” they said.
“It was not a comfortable situation. We were trying to manage it but it was not risk-free by any stretch.”
However, the source contradicted Cummings’s assertion that Strap data was involved in the breach. They insisted that Strap material was kept on separate secure networks.
Among the information that would potentially have been available to China would include diplomatic messages from Britain’s ambassadors around the world. It would also include information that could damage the security and resilience of critical national infrastructure as well the operational effectiveness of UK or allied forces’ military operations.
Cummings said that he found it “ludicrous” that the China spy trial had collapsed because the government refused to describe Beijing as a threat to national security.
“Anyone who has been read in at a high level with the intelligence services on China knows that the word threat doesn’t even begin to cover it,” he said.
“The degree of penetration in espionage, in all kinds of operations, penetration of critical national infrastructure, theft of intellectual property, the whole range of things is absolutely extraordinary. A hundred times worse than it is in the public domain.
“Everybody who has been briefed on the critical analyses of these things from the intelligence services knows this is true. The idea that it is somehow a difficult semantic question of whether to define them as a threat, or how much of a threat, is absolutely puerile nonsense. And everybody in the heart of Whitehall knows this.
“The Strap system was compromised. All sorts of systems were compromised. Fundamental infrastructure for transferring the most sensitive data around the British state was compromised for a long time. For years.”
• Chaos and contradictions over China spy case leave Keir Starmer boxed in
Discussing what he alleged was a cover-up of the breach, Cummings said: “The Cabinet Office’s priority, obviously, was to make sure that no one knew about it.”
He added that it was possible that even Sir Keir Starmer was unaware of the breach.
“I think it’s obvious what’s happened. There’s a political decision made that they don’t want to say certain things publicly because I think, essentially… for the core reason, right, which has been the British state that has prioritised Chinese money over its own security for decades. That is the core issue.”
Cummings said that he had been told by the intelligence services that over many years senior ministers had put economic relations with China ahead of the security of the country.
“The answer was there’s been a political choice made in this country to prioritise Chinese money over security against China,” he said. “Strong Whitehall forces are desperate for Chinese money.”
• Juliet Samuel: Now it’s clear, China hawks were right all along
The latest revelations come after Starmer published critical government evidence that led to the collapse of the Chinese spying trial.
The prime minister told MPs that he had decided to publish three witness statements made by the government’s deputy national security adviser that have been blamed for the failed prosecution.
The decision to publish came after the Crown Prosecution Service (CPS) said it had no objection to making the statements public and insisted it was a matter for the government.
The CPS dropped charges against Christopher Cash, 30, a former parliamentary researcher, and Christopher Berry, 33, an academic, last month after saying the government had failed to provide a statement that “at the time of the offence China represented a threat to national security”. The pair have denied any wrongdoing.
A Cabinet Office spokesman said: “It is untrue to claim that the systems we use to transfer the most sensitive government information have been compromised.” He did not deny, however, that China had obtained years worth of classified material.
