In 1967, the Cultural Revolution was in full swing in China. Influenced by its ultra-leftist ideology, left-wing protests in Hong Kong began to intensify in May of that year, from labor movements and street protests to armed conflicts with the police and bombings of civilians. An atmosphere of red terror spread across Hong Kong society. These riots later came to be known as the "1967 Hong Kong riots"; some have described them as the "Hong Kong-style Cultural Revolution".

Although the 1967 Hong Kong riots were an extension of China's Cultural Revolution, the real trigger came from a labor dispute. In April of 1967, the Hong Kong Artificial Flower Works in San Po Kong fired workers who would not accept their harsh regulations; this in turn sparked protests. On May 6, the workers gathered outside the factory and clashed with management. The workers were subsequently arrested by the police. With influence from ultra-leftist ideology, and with contradictions from long-term lack of social welfare and labor security in Hong Kong society rapidly intensifying, the leftist camp slowly escalated the incident into broader anti-British protest.

At that time, the leftist camp shouted slogans such as "Down with the Hong Kong British Authorities" and "End the fascist tyranny of the Hong Kong British Authorities" and started riots. Lam Bun, then the host of a Commercial Radio Hong Kong program, criticized the leftists' violent acts on the program. A few days later, he was attacked and burned to death with a petrol bomb. This became a landmark event in the 1967 Hong Kong riots. All of Hong Kong society became embroiled in a storm of violence and blood; large amounts of capital flowed out of the region, and there were even rumors that Beijing intended to retake Hong Kong ahead of schedule. The myriad forms of chaos contributed to a wave of immigration out of Hong Kong. In China, the British representative office was also set on fire by the Red Guards, and Sino-British relations came close to collapsing.

The months-long riots only ended in mid-December, after Zhou Enlai asked that the Hong Kong leftists stop the bombings. According to statistics from the British Hong Kong government, a total of 832 people were injured and 51 were killed in the riots. 15 of those killed were killed by bombs. In Hong Kong's mainstream society, "fear of communism" became a deeply-rooted idea; this period also called forth the localist consciousness of the younger generation.

The 1967 Hong Kong riots prompted the British Hong Kong government to change their management strategy, including amending labor laws and shortening working hours. After Hong Kong Governor Murray MacLehose took office in 1971, he accelerated the pace of reform and made significant progress in the areas of education, medical care, clean government, housing, etc. For this, he later gained the nickname "Good Governor MacLehose". Deputy Colonial Secretary Jack Cater, who was in charge of suppressing the riots, described the 1967 Hong Kong riots as a watershed moment in Hong Kong's post-war history: "Before 1967, there was no real channel of contact between the government and the people. After the riots, we set up district offices to improve communication with the people… I don't think there would have been any reform at all [without the riots]."

References: Gary Cheung (Cheung Ka-wai), "Hong Kong’s Watershed: The 1967 Riots"; Yu Ruxin, "Hong Kong, 1967" (Chinese)