I suppose I should make it clear from the start that as I live in Epsom so Grayling is my MP. I'm in no way trying to protect him from anything and I'm not personally a great supporter but I think there are a few things people need to consider when calling for him to be sacked.
He was appointed SoS for transport roundly 26 months ago. The Thameslink programme started about 10 years before his appointment so he could have little influence on that. The DfT - his department - dictated the timetable requirements long before he was Minister.
All Ministers rely heavily on the professional Civil Servants who operate their departments no matter what political party is in power. There's no way in less than two years Grayling could have learnt and understood the complexities of rearranging and operating a new intensive timetable. I worked in the railway industry for over 53 years and I couldn't do it, how many professional railwaymen on here could? He had to rely on his Civil Servants and take their advise. Obviously he was badly advised, the resulting chaos was because he accepted that advise from his own department. But how would he, or anyone else appointed to his role, know the right questions to ask his Civil Servants in such a short period in office?
Removing him from his post wouldn't change anything, it could still happen again under a new SoS for transport because the same advisers from the DfT are still there. If you want him replaced, knowing the political options available to you currently, who do you want to replace him with? Who do you think would do a better job and why? Maybe it would be better to leave him there to sort out the problems, learn from them and to make some changes to his Civil Servants?
The real reason why the timetable change failed so badly was because the DfT - who masterminded the train frequency pattern they wanted in the first place - failed to apply their own EU mandated Common System of Risk Assessment and Evaluation to the timetable change. If they had done so, and combined the Risk Assessments from the TOC's, Network Rail, the ROSCO's and themselves together they would have known there were too many risks unmitigated to ensure there was not a failure.
The DfT are, in my view, totally and completely responsible for what has happened and have failed their minister badly. By all means change the minister but that wont solve the problem in my view, the same Civil Servants will still be giving the wrong advise - and that would still happen with a change of government.
I've not mentioned anything to do with the timetable changes in the north west because I don't have any knowledge of what went wrong there, sorry.