A UK Border Force officer and a Hong Kong trade official based in London have been jailed for spying for China in what is the first such conviction in British criminal history.

Peter Wai, who conducted “shadow policing” operations on Chinese dissidents in the UK, was sentenced to 10 years while his handler, Bill Yuen, received an eight-year term.

After a two-month trial at the Old Bailey, the pair were convicted under the National Security Act of assisting a foreign intelligence service.

Wai, 41, a Border Force officer at Heathrow airport who previously served in the Metropolitan police and as a special constable in the City of London police, was also convicted of misconduct in a public office over his use of a Home Office computer system to acquire details about his targets.

The jury heard that Yuen, 66, a senior manager at the Hong Kong Economic and Trade Office, had taken over the handling of Wai shortly after they met in 2021 to conduct surveillance on dissidents.

In a televised sentencing, Mrs Justice Cheema-Grubb said the defendants’ actions were “deliberate, concerted and serious”.

They had caused “real and significant” harm, leaving those targeted in fear and distress, the judge said.

She described Wai’s attitude towards his misconduct as “arrogant”, saying he had a “sense of entitlement” to do as he pleased.

The case is one of the first to be prosecuted under the National Security Act.

In her sentencing remarks, Cheema-Grubb said: “The offence of which you have been convicted is a grave one. Parliament has enacted the National Security Act in response to the growing reality that the UK now faces persistent, active and often clandestine interference by foreign state actors.

“Modern foreign intelligence activity is not confined to orthodox espionage and may take the form of surveillance and information gathering about dissidents. Conduct of this kind threatens not only the individual victims but the sovereignty of the state and public confidence in institutions and the safety that this jurisdiction must afford to those lawfully present here.”

She said that she had “no doubt” that the two men’s criminal activities contributed to the “fear, insecurity and distress for those targeted”.

The Chinese embassy has said the case was an abuse of law designed to embolden anti-China elements “bent on destabilising Hong Kong”.

The judge told the court she was unable to take into account evidence heard of the men’s spying before the law came into force in December 2023.

The targets of what the judge described as a “shadow policing” operation included Nathan Law, an exiled politician who was the subject of several spying operations, and a second young activist in the UK whose family was being persecuted in mainland China.

Wai also infiltrated Hong Kong pro-democracy groups and was instructed to gather information on politicians, including the former Tory leader Iain Duncan Smith and the peer Helena Kennedy.

Yuen, Wai and a third British national, Matthew Trickett, were arrested with seven others in May 2024 after a failed break-in of a flat in Pontefract, West Yorkshire, that belonged to Monica Kwong, a personal assistant who had fled Hong Kong in 2023 after being accused of defrauding her employer out of £16m.

The seven others arrested, who had recently arrived in the UK, fled the country after being released. The police did not have the interpretation resources to analyse the 200 devices that were seized during the arrest in order to charge them.

Yuen and Wai were charged alongside Trickett, 37, an immigration enforcement officer and former Royal Marine. Trickett was found dead “by his own hand”, the judge said, in a park in Maidenhead, Berkshire, shortly after he was bailed.

Helen Flanagan, the head of Counter Terrorism Policing London, which led the investigation, said: “Wai and Yuen were targeting pro-democracy campaigners here in the UK and sending highly sensitive details about them and their families to the Hong Kong authorities.

“Our investigation, along with the convictions and sentences show how seriously this kind activity is taken in the UK and that it will not be tolerated. It should also serve as a warning to anyone else who might consider doing similar that it is simply not worth it and that when you are caught, you will likely face a lengthy prison sentence.”

Flanagan added that she hoped the sentencing “reassures those living in the UK who may be concerned about being targeted by any foreign state, that we will take action to stop this from happening and that we will do everything we can to help keep them safe”.

Wai had worked as a frontline uniformed officer with the Met based in Hounslow between February 2015 and April 2019 when he resigned.

At the time, he was under investigation for misconduct after he told a supervisor that he used his deceased grandfather’s address on a loan application to avoid tax.

He had also accessed police records as a favour for friends, but police said there was no evidence he had used its database for spying.

Despite the misconduct investigation being held on his files, Wai was later allowed to join the City of London police as a volunteer constable.

A City of London police spokesperson said: “After Wai was arrested, we carried out an extensive review of his time as a special constable, despite assurances this position was not used in his offending.

“Our checks concluded no live misconduct on Wai’s file when vetting was granted.

“Despite his sentence today, Wai is still subject to an accelerated misconduct hearing related to his role as a special constable.

“Our vetting procedures have improved since 2019 and we regularly review our processes in line with national guidance to ensure they are as robust as possible.”