The surest sign that a runway expansion in the 9th Circle of Hell is about to be given the green light:
The western rail access to/from Heathrow is not dependent on the third rwy, it has more to with crossrail although not necessarily officially.
It is also unfinished business because of the failure to provide this access at Airport Junction.
Indeed the western rail access is likely to be in operation long before a third rwy is built (if it ever is).