Barclays Bank is reeling from an unprecedented security breach after thousands of confidential customer files were stolen and sold on to rogue City traders. In the worst case of data loss from a British High Street bank, highly sensitive information, including customers’ earnings, savings, mortgages, health issues and insurance policies, ended up in the hands of unscrupulous brokers. The data ‘gold mine’ - also containing passport and national insurance numbers - is worth millions on the black market because it allowed unsuspecting individuals to be targeted in investment scams.