G550;
The actual list is far too long for on here. But that one ANO article gave them a legal get out with the owner. If he had really thrown his toys after that then I'm pretty sure a court (employment tribunal) would have found in favour of the crew.
I don't know the 139, but I bet the RFM has a pretty long list of limits/restrictions any number of which would have been on the side of the crew.
SND