It's undoubtedly true that those on the various flight decks have no knowledge of this "trial". It seems to take a LONG time for the info to get from NATS to the Airlines to the Ops dept to the Pilots.
Why so? Dunno, but would hazard a guess there is a bottleneck somewhere on the airlines side. The info certainly is sent out to them.
The idea here is soley about better traffic presentation for aircraft exiting the LTMA, which will allow a greater throughput to the en-route sectors. The aircraft may not be at their best speed or even altitude, but they will be moving in an orderly fashion in the right direction.
The alternative is more departure restrictions, be they MDIs or simply holding selected traffic on the ground. Not good for anyone.
Whether a 250kt for all restriction is a good idea remains an untested one.
Bunching remains one of the biggest causal factors of Overloads. In the not too distant future the en-route sectors WILL refuse to accept traffic from the LTMA if poor presentation is leading to bunching and an unsafe situation. Just the same as TC quite rightly stop inbound traffic if neccessary.
Start to look at holding deps at SAM, DVR, CPT etc and stopping any futher departures until AREA can accept the traffic
With regard to LTMA inbounds, yes sometimes presentation is less than ideal and I regret that, and apologise. The reason is the short distance and high flight levels of traffic from Northern France. It's not always possible to restrict A/c speeds drastically in descent because they will not achieve the target levels. If presenation isn't brilliant, you can still "go vertical" and descend in the hold. Not pretty or pefect, but completely acceptable to approach.
There is no suggestion of "bashing" the opposition, be they AC or TC. The idea is to get the greatest (and safest) traffic through put. Examining long held cultures and ideas isn't always popular, but can lead to positive changes. There may be a better way.
Best rgds BEX