Treasury Select Committee
From Consumer Wiki
Treasury Select Committee Second Report here
You can rely on the bank's evidence to the Treasury Select Committee - where they admitted (in a rare case of plain speaking and honesty!) that charges are designed to cover all debt recovery costs. They also likely cover debt write off and the loss of income from bankruptcies & liquidations etc., Thus, what is being charged is not the bank's actual loss as regards an individual customer: see para 50 here
