The mass demonstrations on the streets of Hong Kong present China with its biggest political challenge since the pro-democracy movement was crushed in and around Tiananmen Square in 1989. The parallels between the demonstrations in Hong Kong now and those in Beijing, 25 years ago are eerie – and must be profoundly unsettling to the Communist party leadership. Once again, the demonstrations are led by students demanding democratic reform. Once again, the central authorities have lost control – and risk facing a choice between repression and a humiliating climbdown. Once again, the ultimate question is the power and authority of the Communist party in Beijing.

The differences between Hong Kong in 2014 and Beijing in 1989 are also significant, however. In the intervening 25 years, China has become an immeasurably richer and more powerful country. The Chinese authorities will also be hoping that the current demonstrations in Hong Kong, which started under the banner of the “Occupy Central” movement, will have more in common with “Occupy Wall Street” – which fizzled out – than with the student movement in China in 1989. Finally, the authorities have more leeway than in 1989, if they choose to use it, because Hong Kong is not the capital of the country – it is a regional city, which enjoys a special status under the formula of “one country, two systems” that underpinned the handover from British to Chinese rule.

Under that formula, Hong Kong continues to enjoy a free press and an independent judiciary – freedoms that do not exist on the mainland. The question now is whether Hong Kong will be allowed to take the next step towards democracy and to choose its own chief executive, without the candidates being pre-screened by Beijing.