Chinese banks
Most banks in China require candidates to have a CET-6 or CET-4 certificate. First-and second-tier cities need level 6, and smaller cities need level 4. Even if it is informal, it generally requires four levels. Assistant bank lobby managers in those big cities can be ignored.
Foreign banks
If it is a foreign bank, regardless of informal establishment, it must be at least level 6. Some banks will require six levels of 500, 525, 568 and so on. Moreover, both the written test and the interview should be conducted in the whole UK.
You can't use English at work.
Apart from the translation or writing that may occur in the written test, or the simple English conversation in the interview, it can be said that most positions do not use English at work.
Inquiry and consultation
If in doubt, please consult the public education enterprises in China.