If
this story is to be believed, the sequence of events wasn't as I understood it. Only one train was evacuated to trackside, and that was close to an exit gate onto Wandsworth Common, so marshalling and walking time were not big issues. Before that about six trains were recovered to stations under their own power, and one needed a locomotive but was also moved with its passengers on board. Only then was the last train found to be unmovable, and the power removed, hence its passengers had to stay on board until then.
So it comes down to whether there is an exceptional reason for that to take 5 hours, or whether it did but shouldn't. It might have been a very hot day, so whatever the plan says has to be able to meet the time limit set on that basis.
But note that "if" at the start.