I saw a similar situation to this a couple of months ago (it's not uncommon, sadly).
If it was a Emergency Speed Restriction or Temporary Speed Restriction, and the driver didn't know it was there, he would naturally continue at linespeed through the restriction, thereby doing 90mph (or whatever) through the temporary limit.
All traction units which work over mainline metals have to have an OTMR (On-Train Monitor Recorder), and that will reveal all.
The next obvious question is why didn't the driver know about the ESR/TSR ? If the warning boards weren't set up right he'll possibly be in the clear, but if he didn't see them he'll probably be looking at a 'Safety of the Line Incident' etched forever on his licence, as well as 11 points. Hey ho, there but for the grace of God go all of us drivers
