giolla said this on uk-bi today, quoted by permission:
Why did we book the whole lot for Monday, AFAIR because it was a bank holiday and quite late into things, Cov Uni informed us if we wanted any rooms we had to keep them over the bank holiday evening.
This is slightly ambiguous, but he's since confirmed that it does mean that it's 'if we wanted any rooms over the weekend we had to keep them until the bank holiday evening' ie they either booked them for four nights - given that plenty of the attendees were arriving on the Friday - or not at all.
Now that explains a lot.
I wonder exactly when "quite late" translates as, and I wonder why they didn't kick up a huge fuss about it, and I wonder why they didn't say this months ago...
... but this is looking like the end of the argument over the rooms, isn't it? If the venue, who dunked them in it in at least one other way in early/mid August, did this to them then... wow.
I've been disappointed before, but I'm seeing a rosy light signalling a new dawn here.