“Inasmuch as the Bank of England became the main note-issuing bank and that some of the smaller banks elected to use Bank of England notes rather than issue new notes themselves, the private banks became very dependent upon the Bank of England. They had accounts with the Bank, and kept their reserves with it, and when they ran into difficulties because of a lack of confidence as to their ability to repay depositors on demand (i.e., a run on a bank), they relied on whatever support they could get from the Bank of England.”
Book:Mastering Banking