Is a bank defrauding its customers if it sells them a financial product based on a rigged index without explicitly telling them it is honest?

This question was at the heart of a David-and-Goliath battle that ended quietly last week, when the London Borough of Newham announced a settlement with banking giant Barclays over £238 million of restructured lender option borrower option (LOBO) loans. It was a victory for the council’s mayor, Rokhsana Fiaz, who campaigned for office on a platform of removing the burden of these and other toxic deals negotiated by her predecessor’s administration.