Wasn't at work (but have been called twice to go in due to staff shortage today). I expect that the Notam was not issued because some yes man (I know who was the Ops Manager this am btw so am not surprised) thought they could mitigate the shortage by delaying the aircraft. As soon as the Notam is issued, Two First Names (the CEO) gets notification and is on the phone wanting answers.
There are unstaffed sectors often with no Notam issued but the boys make up the slack and usually get lucky. Seems today this was not the case. And to think that they are going to make 140 odd ATC's redundant in the very near future (budgeted for already).