Some of us may know that in Hong Kong, the majority of banknotes aren't issued by the government, but rather by private banks. As a result, the "ruling authority" for Hong Kong banknotes is kinda useless.
Instead, I propose that instead of putting in the queen/king at the time of issuing, we should consider to add the banks that actually issued the banknote.
Here's a list of banknote issuing authorities in Hong Kong, as per K.N. Boon's Hong Kong & Macau 1846-2017 Banknotes and Coins 2nd Ed.
Asiatic Banking Corporation
The Oriental Bank Corporation
Agra & United Service Bank Limited
The Bank of Hindustan, China & Japan
The Commercial Bank Corporation of India & The East*
The National Bank of China Limited
Japanese Occupation Issue**
The Chartered Mercantile Bank of India, London & China/Mercantile Bank of India, Limited ***
Government of Hong Kong
Bank of China (Hong Kong) Limited
The Chartered Bank of India, Australia & China/The Chartered Bank/Standard Chartered Bank (Hong Kong) Limited ***
The Hong Kong & Shanghai Banking Corporation/The Hong Kong & Shanghai Banking Company Limited***
*Issued very little banknotes, none have been discovered.
** May be grouped under Japan, or its own issuer.
Thanks for your time,
EDIT: The first 6 only issued very few banknotes, and those banknotes are extremely rare, so it might be more useful to group them under "miscellaneous".