According to staff at King's Cross, the 1800 to Edinburgh is "definitely on time", and tickets for that train aren't valid on earlier trains today.
But if I wanted to travel tomorrow or Tuesday, I could use the ticket on any of train that day (as per the LNER website; see quote below). I don't get the logic of that.
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Edit: just to confirm, the 1800
was indeed delayed, despite being assured it woudn't be! It doesn't particularly affect me personally, but some connections have been missed, with others in doubt. This was avoidable. It's great that LNER are allowing people to defer their journeys, and it totally makes sense to allow travel tomorrow/Tuesday, but I just don't get why people who could have avoided a missed connection have been forced to do so, when it was entirely foreseeable. When severe disruption occurs, people should be allowed to minimise the delay to their journeys, if they are in a position to do so.