For many decades, people in Hong Kong enjoyed a level of freedom which was in marked contrast to life in other parts of China. Following the end of the British colonial era in 1997, the Communist Party promised that Hong Kong would remain highly autonomous for fifty years under the 'One Country, Two Systems' principle. Yet when mass street demonstrations erupted in 2019-2020, China responded with sweeping national security legislation, leading to many arrests and the dismantlement of civil society. Mark Clifford, author of Today Hong Kong, Tomorrow The World, shares his reflections with Duncan Bartlett, the Editor of Asian Affairs.