Hong Kong QCs and SCs

Upon the change of sovereignty in 1997, all Queen’s Counsels in
Hong Kong were renamed Senior Counsels. This is a common
practice throughout the British Colonies since the “decline” of the
British Empire. In some countries, barristers can choose to retain
their QC title if they were appointed before the change, such as in
New South Wales, Australia. But in Hong Kong, there is no such
allowance. Former QCs could either go with the change and call
themselves Senior Counsels, or abandon their title totally.
Senior Counsels are only known as SCs and not QCs when they
appear as visiting barristers in the courts of the UK since the Queen
is no longer the head of state of Hong Kong and with the barrister
now being a foreign subject, reference to the Queen is not
appropriate anymore. However, according to the Courts and Legal
Services Act 1990, a Senior Counsel of Hong Kong who is
appearing in legal proceedings before a court in the UK is entitled
to and shall use only the title SC. He / she is accorded the status of
QC for the purposes of those proceedings. This UK law is
reciprocated in Hong Kong in the form of s.31B of the Legal
Practitioners Ordinance of Hong Kong.

In general practice, the title of QC does not get revoked (it is simply replaced by SC in Hong Kong).

So in theory, a former QC can in fact use the title back when the place recognizes the title.