Banking · Negotiable Instruments Act - Case Studies in Negligence

A customer who has maintained a small savings account with a balance of 5,000 for three years suddenly presents a cheque for 45,00,000 for collection. The cheque is drawn by a large Public Sector Undertaking in favor of the customer, but the purpose of the payment is not mentioned, and the amount is wildly inconsistent with the customer's known occupation as a part-time delivery executive. The bank collects the cheque and allows the customer to withdraw the entire amount the next day via a self-cheque. Two weeks later, the PSU reports that the cheque was stolen and the payee name was chemically altered. The PSU sues the collecting bank for negligence. Based on the scenario, which factor is most likely to be cited as the primary reason for the bank's liability?