Fernando Cheung, 64, a former Labour Party member of the Hong Kong legislative council (LegCo), was imprisoned for three weeks over a 45-minute anti-Beijing chant he delivered in 2020.

Contempt charges were brought against him under a law that was meant to protect council members who engaged in non-violent protest in the chamber.

Those protections were weakened, however, by a ruling from the Hong Kong Court of Final Appeal. Lord Reed is one of its members.

The judgment accepted that “the protection of freedom of speech and debate in LegCo is self-evidently an important right”, adding that “it enables members of LegCo to advocate opinions freely and robustly and without inhibition due to the fear of legal proceedings for such speech and debate”.

It also stated that the law had the “purpose of creating a secure and dignified environment conducive to the legislature carrying out its constitutional functions at its sittings without disruption or disturbance”.

The ruling determined that members were only protected from prosecution on the basis of their words, not their actions.

Former Conservative leader Iain Duncan Smith said: “It does astonish me that British judges are prepared to sit in a system that has become completely infected by the autocratic and abusive laws now coming from China.”