She was fired because she leaked information and this fact had become public.
When they can cover such facts, the banks are much less prone to use appropriate punishments.
Many years ago, some employee of a bank has confused my personal bank account with a company account of my employer, and she has sent a list with everything that I have bought using my personal account, during 4 months, to my employer, where the list could have been read by a few dozen people.
Despite the fact this was not only a matter of internal discipline, but violating the banking secrecy was punishable by law where I lived, the bank has tried for a long time to avoid admitting that anything wrong has happened.
However, I have pursued the matter, so they have been forced to admit the wrong doing. Despite this being something far more severe than what has happened to Farage, I did not want for the bank employee to be fired. I considered that an appropriate punishment would have been a pay cut for a few months, which would have ensured that in the future she would have better checked the account numbers for which she sends information to external entities.
In the end all I have got was a written letter where the bank greatly apologized for their mistake. I am not sure if the guilty employee has ever been punished in any way.
After that, I have moved my operations to another bank. Had they reacted rightly to what had happened, I would have stayed with them.