I think the key point here is to tell the Intermediate Director if you need a non-standard speed on the approach. This is the first director frequency to which you are transferred. Telling the final director is just too late.
Incedentally, we fly the 757 into Heathrow using 160 to 4dme. The fleet practice is to actually dial the speed back at 4.5dme and start to reconfigure. Because of the effect of inertia, nothing actually changes until you get to 4dme, so we still comply with the "160 to 4", but at least when we get to 4dme the needles are moving in the correct direction!
G W-H