You can board the sleeper in Glasgow any time starting 2200, with the expected departure time 2340, and arrival in Euston 0707, last vacate-the-train time 0730.

You can board the sleeper in Glasgow any time starting 2200, with the expected departure time 2340, and arrival in Euston 0707, last vacate-the-train time 0730. If you are used to using the service and want to get a reasonable 8 hours sleep then it's totally reasonable to board and go to sleep well before the expected departure time -- indeed, that's part of why they let you board early. Plus, suppose that it was 2340 or later, and they informed you that the train wasn't going anywhere -- by that time of night "sleep on the train and figure out a plan B in the morning" is probably your best bet anyway.