Absolutely the idea of expanding Manchester, Birmingham etc (if the demand exists of course) is a good idea, but certainly not as a substitution for Heathrow. The point I hear made a lot is that Heathrow is a hub airport and is used by many travellers to catch connecting flights to other destinations. But it’s losing out to the likes of Schipol and Frankfurt which have so much more capacity, we should be taking that traffic not letting these other Eurpoean airports steal it from under our noses.
On the whole flightpath issue I’m afraid I have little sympathy, large noisy jets have been flying over SW London for the best part of 40 years, anyone who has bought a house in those areas within that time knew what to expect. I love that the residents of Putney, Richmond, Wandsworth etc complain about noise, I frequently work in those areas and it’s really not that bad, the aircraft are still at 2500ft + when going over. My parents had friends who lived in Hounslow and that was noisy, maybe 500ft above the house (I used to love going there !)
Also I can’t see why having a third runway would make more noise for these residents, there are only a certain number of planes can use a runway per hour, surely all these new flights would be using the new runway whose flightpath would be nowhere near their properties ?
Finally @David_Lockwood I’m pretty sure Heathrow is in Middlesex (though don’t quote me on it !)