It's not actually that surprising, think it was expected, the only surprise is that a decison, any decision, has been taken before the election.
HS2 is taking quite a bit of stick in that part of Middlesex, there are demands for it to be tunnelled across the county. If this was conceded, with existing planned tunnels, the entire HS2 route between London and north west of the Chilterns would be underground!
Not really practical, and very, very expensive and 100% publicly funded (unlike Heathrow expansion incidentally). Still think the whole thing will be scrapped eventually.
The best way from Ringway and Yeadon to Heathrow (and the Thames Valley in general) is by air, and will remain so.
Bagso ... very interesting find there. If confirmed, that HS2 news should help to dampen concerns about further passenger footfall being sucked from the regions to LHR.
Still a danger that economic activity will be sucked towards the capital rather than being dispersed from there, as is the case with HS rail in France and Japan.
That said they are not just getting a new runway and single terminal but a brand new airport, from ground zero, 3 runways plus new terminal capable of 90M !
So "ME3" will soon be "ME4". Yet another reason to get on with it at Heathrow!