Li Keqiang, the man almost certain to succeed Wen Jiabao as China’s premier, came to Hong Kong last week bearing gifts.

Hong Kong, he said continues to “play its irreplaceable role in the mainland’s reform, opening-up and modernisation drive.” Also, Beijing picked the same day to place a CNY20bn ($3.1bn) bond in Hong Kong, the biggest offshore yuan (renminbi) offering thus far. Equally important, it announced measures intended to increase flows of money between Hong Kong and China, such as allowing mainland investors to buy exchange traded funds linked to Hong Kong shares. There are also plans for a joint venture between the stock exchanges in Hong Kong, Shanghai and Shenzen to capture these new opportunities.

Not so long ago, pessimists were counting Hong Kong’s last days as a financial centre. Yet far from diminishing, the city has gained new vigour thanks to its role as China’s most sophisticated financial hub and centre of a nascent offshore yuan business. Last year, Hong Kong topped the global IPO table with deals worth a total $53bn, higher than New York’s $35bn. It remains the principal financial shop window on to China, a position it will hold at least until the yuan is fully convertible.

Yet, Hong Kong cannot relax. There are several uncertainties. First, talk of the yuan’s liberalisation is overegged. Beijing keeps an extremely close watch over its capital account. Cross-border yuan investment is subject to strict quotas or case-by-case approval. If Beijing gets cold feet, it could stop these flows dead. Second, as Hong Kong becomes more integrated into China’s financial system, the exposure of its banks to risk could increase. The city’s regulators have done well at controlling banks’ lending in Hong Kong. But as banks expand deeper into the mainland, regulators must redouble their vigilance. Third, the tide of mainland money is not all good news. Property prices have risen unsustainably. Hong Kong has only limited tools to prevent bubbles given the dollar peg.

Beijing also needs to be cautious. Mr Li rightly identified Hong Kong’s independent judiciary, openness and access to information as important assets. Those attributes are intimately linked with the relative freedoms that Hong Kong enjoys. If Beijing truly values Hong Kong’s role in China’s financial modernisation, as Mr Li says, it should at all costs continue to guarantee those freedoms.