Before we get into any of the details of the above:
the employer had given permission to park outside standard parking places in this situation.
This is noteworthy. Where has your employer been in all of this process?
Are they aware that one of their employees is being sued by the parking company they hired to manage parking on their land, for parking in a space that they had given them express permission to park in?
Did you get this permission in writing?
The driver actually ceased working for this employer shortly after the ticket was issued. They had been an employee for a number of years, it was just unlucky timing. Due to this they didn't really want to bother their ex employer with it, and honestly I thought it was unlikely to get this far, especially with the procedural improprieties.
However they are going to get a written statement from the old employer stating that they were given verbal permission to park here.
I guess the question is that as the person was an employee, with permission, what material loss has their been? In fact had they not parked there the employee's absence would actually have cost the employer money. I am aware that Beavis makes specific material losses a little more shaky, but considering that there is no paid parking here, and no commercial businesses to lose out due to it, as it is only a car park for employees, there could never have been any loss?
*EDIT*
Actually on this note, the specific claim is that it was causing an obstruction. If I were to get a statement from the Head of Security stating that the driver had permission to park here and that he does not consider the location to be obstructive, this would blow them out of the water would it not?