I am a purely local student and I studied in local ENGLISH School and got 6A in HKCEE. Now I am a law student at University of Hong Kong. I would say HKU is within the top ten in UK.
First, I want to say that although English is the language of instruction in many secondary schools and all universities, people just cannot speak English well. Unlike Singapore, our mother language language is Cantonese. In addition to English, we also have to learn Mandarin.
Second, University of Hong Kong is not as comprehensive as Yale. Many subjects like Astronmy, Forestry, Marine Sciences, Archeaology, Geology, Ancient History, African studies, Latin Americal Studies, Library studies (There must be more examples) are not offered here. Nevertheless, I know that some visiting students here come from Yale, Columbia, UC, so the academic standard of HKU must be good.
Third, universities in HK are East-Asia-Oriented. Chinese-related stuffs are our strength, so probably in these areas HK unis are academically better than Oxbridge and Ivies. I would say even SOAS is worse than HKU in these areas.
For instance, Faculty of Law in HKU has a very very strong Chinese law team which is led by a prominent law professor, Albery Chen.
Next year, I am going to transfer to University of Wales, Aberystwyth to study international politics because so few international politics courses are offerred in HKU. What I want to say is that it is quite pointless to argue which uni is better and which uni is worse. Oxbridge is strong indeed, but they cannot be strong in all areas of academic studies. The problem inevitably boils down to resources and the actual academics employed. Usually, only 10-20 academics are employed in each department, so it really depends on the personal quality.
Prestige is an intangible and sociological phenomenon which is subject to geographical variation. HKU is more famous than warwick, Nottingham and perhaps LSE in HK!
Thanks