Bookworm,
you are correct... large scale 'joined up thinking' with all the european states would be needed to make the best go at a decent system... it might happen in the future, but one of the difficulties will be getting countries to relinquish sovereign airspace...
Flowman
the system NATS is bringing in is more along the lines of an extended EAT display, allowing controllers to see what the EAT is for each aircraft and to (hopefully) allow them (the controllers) to issue speed instructions etc that tie in with the EAT, to minimise or negate holding.
The problem could be getting adjacent stand alone sectors talking to each other when they are controlling aircraft inbound to the same hold facility... it could cause more problems for the TC guys instead of alleviating them, time will tell.
If it goes to plan, it will actually be a great benefit.
As for holding in the LTMA - to gain the best and most efficient use of a runway that has over 90% occupancy rates, you need to have a constant supply of aircraft to vector onto final. That is why Heathrow runs best (most efficiently) when it has a few aircraft in the hold.
Remember we are purely talking about the efficiency of runways here, when you have a dedicated landing runway.