Are the environmental issues really spurious - more flights means more noise, and it ain't cheap.
When you are talking about a project that is likely to not be operational until the 2030's at least then using todays air quality measurements isn't accurate. Especially when you look at the move towards electric vehicles and more more eco friendly aircraft engines. Then there is the argument about less aircraft in the hold.
Talking about the differences in the level of regional infrastructure expenditure isn't just a "fan club" issue.
The Manchester lot are behind Gatwick expansion so it's not about north/south. They see a hub at LHR as a threat to their spotting books.