This past weekend, as protesters and riot police fought in the glitzy surroundings of a Hong Kong mall, one officer made the mistake of getting separated from his colleagues as he viciously hit a young protester. A few minutes later, he tripped and ended up on the ground - only to be piled on by dozens of protesters, who took evident delight in beating him.

It was a sad sign of how hated a police force once praised as “Asia’s finest” has become. But it was also part of a legacy of police brutality, and subsequent violence from protesters, stretching back to the colonial era—and continued by the key role that British officers play in the Hong Kong Police Force (HKPF).

The HKPF stopped recruiting from foreign services in 1994, but older British officers left over from the handover continue to dominate its senior staff. At the center of the heavily criticized police response to the recent protests are three senior British police officers: chief superintendent Rupert Dover, senior superintendent David Jordan, and superintendent Justin Shave. June 12 saw HKPF officers use rubber bullets, beanbag rounds, and pepper spray on peaceful protesters and riot police beating unarmed demonstrators senseless, on the orders of Dover and others, and in the most infamous incident of all, Shave ordered a tear gas round to be fired at an unarmed approaching legislator. All three were later by Shadow Foreign Affairs Minister Helen Goodman for their callous actions.

Yet beyond the role of individual personnel lies a deeper story of brutal post-colonial policing.

In 1981, shortly after Margaret Thatcher’s government took office, an unlikely meeting took place at a nondescript conference center in Preston, a small town in the north of England. Police in the United Kingdom, widely criticized for their handling of the race riots that same year, had requested help from Roy Henry, the then-police commissioner of Hong Kong, who ordered one of his most senior officers, Director of Operations Richard Quine, to the U.K. to tell them all he knew.

Some 14 years earlier, the HKPF had brutally suppressed the worst violence in the city’s history, as pro-communist rioters launched indiscriminate bomb attacks against civilians. The British police were eager to hear exactly how it had been done—and to reproduce the same tactics against demonstrators in the U.K.

In 1967, with the Cultural Revolution in China reaching its crescendo, communists inspired by the activities of the Red Guards in the mainland waged a protracted insurgency in Hong Kong against the colonial government. More than 200 people were killed, including a radio journalist burnt alive by communist attackers—with some rioters beaten to death by police. Hong Kong’s status as a colony was exploited by the HKPF as a potential testing ground for new strategies that would be deemed too extreme for use in Britain.

The scholar Lawrence Ho details the police measures as encompassing the “liberal use of force and lethal weapons [and] widespread assault and imprisonment of demonstrators,” coupled with the imposition of oppressive legislation and curfews. Revolutionary new policing techniques widely used across the world today, including “kettling” and the first-ever use of tear gas and short shields by newly instituted riot squads, were first tested in the summer of 1967 by the HKPF.

However brutal the measures, the HKPF’s success in quelling the violence marked the beginning of an era of widespread public support for the force, which was to bask in the warm glow of its newly granted Royal Charter in 1969—awarded for its handling of the riots—and its reputation as Asia’s finest for decades to come.

Quine’s recommendations to British police included instituting dedicated units of officers—“riot suppression units,” each with a particular responsibility to fulfill, such as arresting demonstrators (“snatch squads”), firing tear gas, or crowd intimidation. To this end, Quine proposed initiating a program of 10-week crash courses for officers in techniques including kettling, the use of tear gas, and crowd control, with an eye to rapidly improving the British police’s ability to respond to civil unrest.

The training came too late for the race riots—but the techniques were on full display in British police violence against miners during the 1984-1985 strike, most infamously in the Battle of Orgreave. These techniques were eventually codified amid total secrecy in a file titled the “Public Order Manual of Tactical Options and Related Matters,” an infamous document that only became public in the aftermath of Orgreave.