I think it's wrong to expect to be able to issue EATs 150 miles out. That's almost an hour from touchdown, there's no way an EAT will be accurate then.
If AC or TC 'outer' sectors are pressured for an EAT can't they give a best guess estimate or quote the delay for the aircraft just entering the inner holds as a guide?
When I've done EATs I've been pushed for times by Midlands controllers but I've kept them waiting while I arranged a stack swap which facilitated a better order for TEAMing and maybe knocked 3 mins off the delays.
What are we trying to do here, expedite the traffic or give very early delay info?
Pilots should be aware that the earlier the landing order is decided the less efficient it will be.
Having said that, the biggest problem for delay management that the move to swanwick has produced is the EAT PC and landing rate monitor is not as easily accessable for the Heathrow controllers as it was. We can't update is as we used to or use it to guide the traffic manager in chosing the best landing order.