People book journeys in advance. If I was looking to book a journey to or from London or the North East last week, I would have booked it with Grand Central. Even now, LNER will be operating under a cloud. Why risk a cancellation on LNER? People on this forum with knowledge of the railways may know what's going on, but the general public will only have heard horror stories on the news of safety issues, broken trains and entire fleets withdrawn from service. This has been a public relations catastrophe for LNER and it's something they won't recover from quickly
The people I talked to at work today hadn't even heard of the problem.
And this is somewhere that 800's provide the service to London.