On the edge of Hong Kong’s Victoria Harbour, workers are building a cavernous station that will be the terminus for one of the most expensive high-speed rail links ever constructed. The $11bn fast train linking Hong Kong to mainland China is meant to be a showpiece for integration between the semi-autonomous territory and its mother country.

Instead, the over-budget and behind-schedule project has turned into a symbol of the deteriorating political and economic relationship between Beijing and Hong Kong. It could be a foretaste of the profound difficulties that lie ahead for the global financial centre.

To smooth rail departures, the Hong Kong government is planning to place Chinese border police inside Kowloon station, much like French police conduct checks on outgoing Eurostar passengers at St Pancras terminus in London. The proposal might have been convenient for travellers but was worrying Hong Kongers, even before the detention last year by the mainland police of five Hong Kong publishers who sold works critical of China’s ruling Communist party.