The obvious alternative is to find a plug that fits the socket and simply change the plug.
The plug you were showing is the old British 546
BS 546 - Wikipedia, the free encyclopedia
So far in HK I've only seen the 15A Variant, predominantly used to connect aircons.
If I were you, I'd get one of these multi-socket outlet, (dunno the proper english name, those that take all kinds of plugs with 5 outlets in a row) and one separate 546 plug and then follow PDLM's advice and replace the plug of the outlet. I found both the plug as well as the the multi socket outlet in CUHK's tiny ParknShop. Shouldn't be that much work to find anywhere. Ask a local colleague for the chinese name.