In the late summer and early autumn of 2019, Hong Kong was engulfed in turmoil. In August, the territory’s airport was occupied by protesters, briefly halting its operations, and a few months later the Chinese Communist party’s celebration of its 70th anniversary in power was overshadowed by yet more violent clashes on the territory’s streets.

At the height of the uncertainty in Hong Kong, Chinese financial regulators convened an emergency meeting in Beijing, according to people familiar with the event. If the worst came to the worst in China’s premier international finance centre, the regulators asked the financial and legal experts invited to the brainstorming session, what could they do in Shanghai to help that city step into the breach?

The answer, it quickly emerged, was not much. When Chinese lawyers in attendance said Shanghai would need to create some sort of Common Law enclave, free from party interference, to match the international seamlessness of Hong Kong’s judicial system, it was recognised that was politically impossible.