Prophead wrote: "You have still not answered my question though Ozzy. How is scrapping a project that would be beneficial to the whole of the UK and building one only helping the SE a reasonable answer to the North/South funding imbalance?"
You have overdosed on too much HAL propaganda. R3 is not net-beneficial to regional UK. Locally-awarded construction-related contracts will be short-term, thinly-spread and competitively-tendered. They won't revitalise the regions. Those much-vaunted PSO-funded extra domestic flights (if they happen) will be more than offset by the loss of a forecast 74000 fewer direct flights from the regions per annum by 2030 rising to 161000 per annum by 2050 (Transport Select Committee - June 5th). And many of these will be high-impact long-haul scheduled services. Regional UK is best served by retaining and building upon direct long-haul services of its own. Meanwhile, one-stop connecting flights are already easily available via more user-friendly hubs than LHR when required. Probably at cheaper fares too.
London's capacity-crunch really is a SE-specific issue. And given that the strongest demand growth is driven by short-haul budget airlines, new runways at Gatwick and Stansted provide a much better solution at a far lower cost. Two new runways in the SE mean at least double the new capacity of one at LHR anyway. Especially in view of the latest proposal for an extended eight hour night curfew at LHR. Deduct 90 minutes of movements times three runways at times of high-value demand and that is devastating to the business case for LHR as presented so far. All financial calculations must be reworked. Note too that the tax income windfall you attribute to the build programme applies similarly to alternative projects.
Finally - but not least - Regional UK is by far best-served by overdue investment in its own infrastructure priorities. Trickledown is comprehensively discredited. Opportunity cost is real. Billions in public funds allocated to Heathrow access works cannot simultaneously fund regional priorities. Your notion that that road and rail upgrades around Heathrow "need doing anyway" - so they will be funded - is a very entitled way of thinking ... peculiar to London as that is the way things have always been there. There are lots of "desperately need doing right now" projects across regional UK but they simply don't get funded at all. That needs to change urgently. And making regional infrastructure competitive again really will bring national benefit.