DRUK
If T6 is built west of the MSCP of T5, and then they both become Heathrow West, so it is not an extension? T6 was originally North of the airport with the 3rd runway.
The A304 will be moved for the comfort of this "extension" as it is on the plan, together with the disappearance of the A4 Bath Road. None of the consultants at the local briefing could explain about the movement of these roads.
Neither could they explain fully the ability of all aircraft to "touch down further along the runways to reduce noise"
T09L