Very grateful for those replies.
So, a cynic might say that this is a weak reaction to the problem of under-capacity, by introducing rules rather than fixing fundamental problems. I’d find it hard to argue with that.
Someone more forward-thinking might ask why the system can’t flex more and what the economic and environmental costs are of this move.
So my next question is, what inhabits the space between flow control and coordination? Why can there not be some form of medium-term flow control/coordination which tries to optimise, for both controllers and pilots, rather than restricting? Which looks for genuine overloads, not hypothetical ones, and also spots opportunities to exploit airspace optimally?
As I say, apart from a few TRUCE and STAC events, and some other liaison which has never focused on this issue, I’ve been out of the ACC world for a long time, so it may be someone can cast a more positive light on this?