idk. Underwriters have certain liquidity requirements for banks offering credit - The bank is considered 'liable' or committed to the amount of outstanding credit made available to their customers, even if the customers are not accessing the credit lines at present. For barclays to loan more money to new customers, to meet underwriting (insurer's) guidelines, they may need to curtail some of the outstanding credit available to current customers. So, if they have customers who have never or very rarely accessed their full credit limits, they will cut those limits down in order to make extra 'room' to make loans to other customers who will 'use' their credit (and pay interest back to the bank).