His work was in the Scottish Development International section and his main responsibility was to encourage the mainland business community to invest in Scotland.

[2] His family and friends worried that he was arrested because he had expressed his support for the ongoing 2019 Hong Kong protests through his social media accounts.

His disappearance caught public attention, since it was reported that officers at the border had been searching civilians' belongings and phones to identify anyone who had attended the protests.

[2] The British Consul General stated that they were "extremely concerned" about Cheng's disappearance and asked the Chinese authorities to release more details about his detainment.

[5] On 21 August, at a press conference held by the Chinese Ministry of Foreign Affairs, spokesperson Geng Shuang revealed that China had detained Cheng using the Security Administration Punishment Law, which covers mostly minor offences.

[8] In November, Cheng published an article named "For the Record: An Enemy of the State" on Facebook, in which he disclosed the details during his detention and his side of the story.

[1] He recounted that he was handed over to three plain-clothed officers who he suspected to be secret police after he was escorted back to Shenzhen from West Kowloon station.

[1] Throughout the process, the agents verbally assaulted him, calling him "worse than shit", "enemy of the state", and that he did not deserve any "human rights" as he was an "intelligence officer".

[12] Before he was allowed to leave, the police reportedly threatened him by claiming that he would be "taken back" to mainland China from Hong Kong if he disclosed "anything other than 'soliciting prostitution' publicly".

[1] When asked by a reporter from BBC News if he paid for sex, Cheng said he visited a massage parlour for "relaxation" after his business trip, and that he had done "nothing regrettable to the people I cherish and love".

[1] On 21 November, Chinese state media China Global Television Network (CGTN) released his confession video and a two-minute long CCTV footage of him visiting a clubhouse.

In the confession video, wearing prison uniform, Cheng claimed that he did not contact his family or seek help from a lawyer because "he felt ashamed and embarrassed".

“We found the individuals (Simon Cheng and Gui Minhai) concerned were unfairly treated and had their privacy unwarrantably infringed,” Ofcom said, adding that the broadcaster had “failed to obtain their informed consent to be interviewed.” It concluded that “material facts which cast serious doubt on the reliability of their alleged confessions” had been left out of the programmes, which aired pre-trial “confessions” of the two men while they were being detained.

I summoned the Chinese Ambassador to express our outrage at the brutal and disgraceful treatment of Simon in violation of China's international obligations.

[19] Amnesty International responded by saying that Cheng's account of his treatment during his detention aligned with the "documented pattern of torture" commonly seen in Chinese prisons.

He added that Beijing has a history of forcing detainees who have ties with foreign governments to record confession videos to deflect criticism.

As China imposed a national security law on Hong Kong, Cheng collaborated with other exiled activists, including Ray Wong, Brian Leung and Lam Wing-kee to launch an online advice platform named "Haven Assistance" to help Hongkongers who were also facing political prosecution and seeking asylum.

[26] On 30 July 2020, the Hong Kong police announced that they had issued arrest warrants to six exiled activists including Cheng, Nathan Law, Ray Wong, Wayne Chan, Honcques Laus, and Samuel Chu for breaching the national security law "on suspicion of inciting secession or colluding with foreign forces".

[27] On 14 December 2023, the Hong Kong government issued an arrest warrant against Cheng and put a bounty of HK$1 million on his capture.

[29] On 12 June 2024, the Hong Kong government revoked the passport of Cheng, exercising powers that it had been granted under the Safeguarding National Security Ordinance.