MI5 chief shares his 'frustration' after case against alleged spies is dropped

The head of MI5 has acknowledged his frustration at the failure to put on trial two Britons accused of spying for China.

- Dan Sabbagh

In an apparent rebuke to prosecutors who dropped the high-profile case last month, Ken McCallum insisted he would “never back off” from confronting threats from Beijing.

He said China posed a national security threat “every day”, although the wider political relationship was a matter for the government.

A China-related spy plot had been disrupted “in the last week”, he said, though it is understood not to have involved parliament.

The number of people under investigation over all state-based threats is up 35% in a year.

Giving a long-planned annual update, MI5’s director general was asked to comment on a surprise decision last month by the Crown Prosecution Service to abandon the prosecution of Christopher Cash, a parliamentary researcher, and Christopher Berry.

“Of course I am frustrated when opportunities to prosecute national security threatening activity are not followed through for what ever reason,” he said, though he added that MI5 had been successful in halting the activities the two men had been alleged to have carried out.