Apparently the laptop was pinched from the home of an employee who only told his boss what was on the laptop three weeks later, when he came back from a holiday abroad. Only then was an investigation launched.
It's not clear exactly what information was on the laptop - Nationwide is not telling us because the laptop is still missing - but what we have been told is that there is no chance that the leaked information could lead to identity fraud. The laptop contained no balance information, passwords or PIN numbers.
FSA enforcement director Margaret Cole said, "Nationwide is the UK's largest building society and holds confidential information for over 11 million customers. Nationwide's customers were entitled to rely upon it to take reasonable steps to make sure their personal information was secure."
Nationwide bosses have written to all customers to apologise for the mistake, saying "We wish to emphasise that there has been no loss of money from our customers' accounts as a result of this incident."