The three UK operators all use the same Met Office tool and follow the same rules. I surmise NHV also do, but don't know for certain.
As previous messages have stated, the 'forecast' no go areas do seem to change on a regular basis. So it is quite feasible that a longer range flight would launch based on the forecast that crew were presented with, and a later shorter range flight might have a forecast that would preclude them from launching into the same area that the earlier flight might now be flying through.
Today I saw flights recovering back to Aberdeen at a time the tool was saying Aberdeen was red, so no flights will launch.
It's all a bit messy, but rest assured there is no conspiracy and there is no difference in rules between operators. What does change is the forecast, and it changes far too frequently! We do try our best to get you guys home, but we do have to follow the rules. Hopefully you view that as a good thing.
As for tomorrow the predicative tool only looks ahead by up to 6 hours, so tomorrow morning is not yet visible. Overnight it looks to be changeable :-) Most of the weather seems to be East of a line from Harding to ETAP. Later, East of Shetland doesn't look good.