Firstly, the S.E. will need to retain point-to-point airports. Thus LGW and STN will need to stay, to provide for the Low-Standards airlines and their desperate travelers. There is no point clogging up a world-class hub with harp logos, and these carriers would not want to go there anyway. Too expensive and too crowded for locos (20 minute turnaround at LHR anyone?).
Look the only way we can legally make airlines to use the Thames Hub airport (THA) is to close all other airports in the area, if we just close LHR, then BA and others would spend huge amounts of money buying up slots at LGW (because it is more conveniant to use that airport than the THA), if you close both LHR and LGW, then the same will happen, only it will be both Luton and Stansted
Hence why the THA would be a white elephant even if only some of Londons other airports would remain open
If Ryanair refuse to use the THA, then they will shoot themselves in the foot by locking themselves out of the London + SE market, however I am sure Easyjet (who use serve CDG for example) and other LCCs would use this airport
Also I don't think 6 runways are enough (you would need 8, most of all when you are dealing with all of Londons air traffic) and Looking the at project itself, £50 Billion is not enough consiering the size and the need for decent transport links for this airport (you would need several HSRs for a start)
As to the issue of bonds, if you set a fixed rate for the bond this simply becomes a government bond, wholly backed by the government with very little connection to the airport. And while general returns on investments are low at present, making 4% attractive, would you really want to trust your money to a European government in the present climate? I don't think many big players will, they will prefer property or overseas investments over the UK government. And if you do attract big money for this project, are you not simply extracting money from the economy and reducing economic activity in other sectors?
In the current climate, the only really way of financing such a large project, is through Quantitive Easing. The government has already printed some £300 billion, which could easily have funded Silver-Boris airport six times over. Instead, they gave the money to banksters, so they could continue paying each other fat bonuses. So when large industrial corporations get into financial trouble, often through sheer incompetence, the government sticks two fingers up at them. But when the banks get into trouble, often through sheer greed and incompetence, they get bailed out and given a bonus. It sounds very much like the USSR's failed economic model.
Did anyone here feel any benefit from all this largesse to the City of London? No. Alternatively, had this money been spent more wisely, we could already have had - a new London airport; a new nationwide TGV network; three new regional airports; four new shipping ports; and some money left over for scientific R&D. What would have been better for the economy and the people, eh? What would have provided more jobs and more economic activity, and made the UK a better place to live in - creating a first-class travel infrastructure for the UK, or another fat bonus for an incompetent bankster?
For a start the bonds are aimed at the gerneral public, who have spent the last 4+ years getting dismal returns from their savings account, Also you have to take account many people and business are putting their money "under the bed" in other words they are not spending the money because they have little confindence in the economy, that money could be used to kick start the economy of this country (and help it recover and grow again)
I agree on the fact that out economic and poltical systems are not working for the people of Britain and that the only way we can solve it is by radical reform
However, The government has not printed enough money to fund 6 Silver-Boris airports, but rather 2
Personally, I am rather unsure of funding a project on printing money, but I don’t think it is a bad idea to fund the whole project with £100+ Billion woth of QE, because unlike their previous attempts, it will be a great help to the UK economy
Plus due to the fact there is no poltical will to expand the current set of Londons Airports, this is pretty much the only way to expand out airport capacity