I'll be on the case tomorrow morning and find out what the fuck is going on.
General feeling on here is it's shite and to ignore, also heard that in plenty other similar situations before, but rather than risk it I will be contacting them.
Just don't admit to being the driver. They have to prove it was you that was driving, if they can't then they have no case. You can stop all the follow up letters and demands by responding to the initial fine saying that you were not the driver and are not required to disclose who the driver was.