The burglary occurred in August, when an employee’s laptop was taken in a domestic break-in, but Nationwide has only just informed its customers that sensitive data may have been stolen.

However, the company is adamant that no security breach has resulted from the theft, and has reassured account holders that their money is safe.

Nationwide said that the delay in informing its customers of the possible risks was because it did not want to create anxiety among its customers. In addition to this, extra security measures have been added to its system.