Out of interest, what organisations are "anti-Heathrow" ?
I'm not aware of any, with the possible exception of the Mayor of London's kitchen cabinet (though his views don't reflect those of the London Assembly).
Are you getting confused with organisations that oppose Heathrow expansion ?
Off the top of my head, HACAN comes to mind, it has been campaigning on "noise" issues for many years, long before expansion came back onto the agenda.
AFAIK, and this could be wrong, it is part of the vocal anti-Heathrow minority most of which lives miles away from the airport.