As part of a speech to Parliament on Monday, transportation minister Ruth Kelly said that the details had been lost by a third-party contractor, Pearson Driving Assessments, in May of this year.
Pearson Driving Assessments, a private contractor for the Driving Standards Agency, informed the agency that "a hard disk had gone missing from its secure facility in Iowa City, Iowa," said Kelly. "The hard-disk drive contained the records of just over 3 million candidates for the driving theory test."
The lost details included names, postal addresses, e-mail addresses, and telephone numbers of people who participated in the test between September 2004 and April this year.
"The lost hard disk did not contain bank account and credit card details, driving license, or national insurance numbers," said Kelly. She added that the disk had been formatted specifically for Pearson systems "and, as such, is not readily usable or accessible by third parties."
Kelly said that the Information Commissioner's Office in the U.K. had been informed of the loss and, while being concerned at the scale of the breach, had deemed it unnecessary to contact individuals involved as there appeared to be "no substantial risk" connected to the loss of their data.
Pearson now uses electronic transfer in place of hard disks, said Kelly.
The speech was made by Kelly in response to the loss of more than 7,600 motorists' details by the Northern Ireland Driver and Vehicle Agency earlier this month, and follows the loss by Her Majesty's Revenue & Customs of personal and financial details on 25 million people claiming and receiving child benefits. Kelly divulged the learner-driver data loss during the speech "in the interests of greater transparency."
Tom Espiner of ZDNet UK reported from London.