Thanks for the suggestions, KB!
I'll certainly try the lacing techniques that are shown in the YouTube videos, but I don't think I'll tie a knot as shown in the first one of the links - surely that will make getting your boots off more difficult unless you undo it, which won't be easy by the end of the day.
You're right, too, I really ought to get some new socks (Christmas is coming, they'll be the sort of socks I won't mind receiving
) but I'm not going to give up wearing meraklon inner ones under them, that would be breaking the habit of a lifetime. Unlike some people I've read about on this forum, I never get blisters. Who knows, this could be the reason.