Shortstripper
Perhaps the glider pilot is using it to aid his or her goal (distance record perhaps). If you're not happy get an IR and fly in class A. Apart from crossing under permission there be no gliders there!
How do you suggest that BA continue their service into Newcastle then?
I am sure that the professionals will be able to confirm many other instances of commercial traffic being unable to make a whole journey in controlled airspace, let alone class A.
Gliding in clouds will continue to be legal, until a serious incident happens and the debris lands in full sight of her Majesty's Press. After that, I wouldn't be surprised to see a rapid change of the laws.
Then again, due to the low probability of two aircraft occupying the same piece of cloud at the same time, it could be a considerable time until this happens.