If yu doubt this is a wider banking matter, you only have to look at the reaction.
Banking is a staid industry, at least domestically, and has clearly been shocked to its core by what Farage has uncovered.
You also don't get the prime minister, the chancellor, and some other senior bloke in the treasury poking their noses in if there's nothing to smell.
Oh, and don't forget MPs of various parties who have said they have their own PEP stories to tell.
You could also look at what's not been said.
If the problem was solely about Farage, the other banks would not be slow to point that out.
They would all be saying 'come to us - we are bankers not debankers'.
But of course they cannot say that, because they know they are all involved.