It was only when the design was able to pass strict enterprise-grade Zero Error standard of 400 units surviving 500 hours of the toughest continuous testing without a single error or failure that the drive was manufactured.
Correction 28 September 2012: The main figure in this story has been amended from 50, 000 to 11, 500 after it emerged that there had been an error in the calculations carried out for Panorama by the School of Health and Related Research at the University of Sheffield.
There was also a technical error with an automated phone system that told more than 12, 500 voters in another county that the election was on Wednesday.