The information is stored on one host computer via the Government Digital Services. So that information isn't transferred onto personal computers or other hard drives.
I would have to ask our technical guys to perhaps write with further information on the exact procedure that is taken to ensure full deletion. With this current system, which has only been in operation since 2010 and is due to finish in 2015, we haven't actually deleted any information from the system as such yet. But I'm sure there is a process in place that we could inform you about.