The criteria applies between an employee and a review committee of the same organisation.Again you ignore statute and use google to inform. Unfortunately, it looks like you’ve found another US example, though you may be misquoting Adam v Ward [1917] AC 309. The defamation act limits common law qualified privilege - your example does not align. A customer is not an employee, a risk review board does not have a statutory duty beyond those already discussed to research the political views of a customer. The report does not limit itself to research. It goes much further.
You also ignore the bbc briefing which cost the briefer her job and caused the bbc to apologise. Noting also that Coutts issued an apology too, so I’m not sure coutts dispute Farage’s version anymore given the total climb down.
"... a privileged occasion is ... an occasion where the person who makes a communication has an interest or a duty, legal, social, or moral, to make it to the person to whom it is made, and the person to whom it is so made has a corresponding interest or duty to receive it. This reciprocity is essential."
The employee had a legal and moral duty to inform the review committee.
It was Farage who further communicated the report to the public. Until then it was private within the confines of Coutts.
The BBC briefing was true, Farage account was threatened with closure because of the funds.
The person who resigned accepted that she should not have commented at all. She was providing the genuine reason for the closure of the account, which was true and could not be considered libel.