Tell me about it. Coming back from my last visit to the UK I had a 2 hour delay, spent sat on the plane at the stand. The cause? French ATC were on strike in Marseilles but because of that we couldn't transit French air space at all. There was bad weather over Germany, which caused lots of delays in their air space, so we had to wait for a slot. We had to be on the plane ready to go in case a plane in a slot before us failed to make it and we could take it over.
I can remember suffering a delay at Chania many years ago because Greek ATC were on a work to rule. They are only supposed to have so many planes in Greek air space at any one time. Normally they ignore this rule, provided the planes are sufficiently far apart, but enforce it exactly when there is a work to rule. The plane that caused the excess and prevented us taking off was flying across northern Greece from Italy to Turkey. It took around 45 minutes to clear Greek air space. If we had taken off on time, aimed directly for it and set maximum speed there was no way we could have collided with it.