General view from my railway friends is that the evacuation took far too long and that there's be a major investigation into this mess.
I personally think it didn’t take too long. You’ve got to get staff to site, be that NR, BTP and firefighters and then make safe the overheads safe.
You’ve got 7 stranded trains each with a considerable number of passengers onboard. Without substantial numbers of staff, that’s never going to be swift.
It doesn’t help when passengers self evacuate which means resource has to be deployed to remove them from danger.