I've been giving this a little thought (I don't do big thoughts) and a couple of points occur to me. Yep it probably did contravine the ANO to close. I can't help imagining the scenario.
Amalgamated widgets decide to book their conference at Sywell (perhaps because it's cheaper...budget control in these straightened times etc etc) The thought dosen't occur to MR D Rector that since the venue is at an airport there might be some...gasp...aircraft noise. Anyhow, the day dawns and the conference gets underway and...shock horror... there is aircraft noise interupting detailed discussions of widget sales trends and the new kevlar-cardbon widget under development. Mr D Rector can't believe and storms off to see the airport management stomps his feet and pounds the desk with his fist and wins the day.
Re the fly in there is little chance that Consolidated Widgets (a rival) will be holding their conference on a Saturday so the scenario is unlikley to repeat...of course unless the apple of Mr D Rector's eye, his daughter Petunia is getting married that day and he got the hangar for the reception as part of a package deal...
Nah I think it was just an error of judgement by the airport who are entering a new area of business and are still climbing the learning curve so it might be as well to cut them a little slack.
'course if they do it again.....
I'ver just read on another thread that it was closed for 2 1/2 days I'd thought we were talking a few hours. Hmmmmm think I've just reeled in a bit of that slack.