Thanks for your question Chevvron - which does a good job of showing just how much of a newby I am to this subject
I am primarily intrigued by the huge job undertaken to evacuate the airspace over the Atlantic on September 11th, so perhaps my first information target might be Shanwick. But possibly the unprecedented demands of that day spilled pressure over to the other two units?
If anyone is aware of any website or book that discusses that day, I'd be glad of the heads-up.
ron