then even in an emergency
It is lawful for the Rules of the Air to be departed from to the extent necessary:
(a) for avoiding immediate danger;
So.... as long as you're prepared to comply with
If any departure from the Rules of the Air is made for the purpose of avoiding
immediate danger, the commander of the aircraft must cause written detailed
information about the departure, and of the circumstances giving rise to it, to be given
within 10 days of the departure to the competent authority of the country in whose
territory the departure was made or if the departure was made over the high seas, to
the CAA.
Then infringing controlled airspace in an emergency as a last resort when you've exhaused absolutley every other possibility is something that would be silly for anotherthing to ban outright !
However, for the avoidance of doubt, my point of view is you shouldn't be flying so close to it in the first place !