splitduty,
As a retired airline pilot, I share your concern about this unprecedented action by NATS; taking the decision out of our hands. But I think this was probably government intervention, as said yesterday? No doubt, the readiness of the authorities to intervene has magnified since "9/11".
The spectre of numbers of 200-tonne gliders over built-up areas was probably too much. Once they have raised the alarm, which operator can tell if his insurer would pay up?
Chris