Thanks pilot2684 "Legally" covered in the T&C's when you buy a ticket I guess.
How time rolls by with rectifying faults. When you think something is going to be a 5 minute fix it ends up not being for various reasons, and if told something should only take an hour max you naturally hold off for that, etc. etc.
I read somewhere that in the U.S. there was a class action by pax against an airline for being held on board for many hours due to some issue, and the airline settled. Also heard over there they have some proposed rule/legislation that would mean a max 3 hour limit to holding pax on board on ground.