If London is under water in 20 years time then it won't need any runways, whether at Heathrow, the Thames Estuary or elsewhere.
Meanwhile, the Estuary option seems to be cheaper and less nuisance to neighbours.

Paul, London, UK

One problem:

Won't the new airport be under the sea in 20 years (climate change etc.)?

Didn't think it through, did we?

Will, Worcestershire, UK

Bring this failed government down and other schemes will have a chance, with Labour in government the third runway at Heathrow will go ahead. Labour are control freaks and will never back down on anything as we have seen so often.

D Case, Newquay,

Remember that Heathrow Airport is now in private ownership. If economics should dictate that its site be redeveloped into housing or anything else then presumably the proceeds of this redevelopment would go to its Spanish owners, who are the new shareholders of BAA. Whether they will then spend these proceeds on a new airport for London will depend on whether they want to and are allowed to.

Paul, London, UK

Eventually common sense will prevail but only once a lot more money has been spent on the white elephant that is Heathrow. Witihn the Department of Transport, the divine received wisdom is that London's main airport must be at Heathrow because that was the ancient order of things handed down from Abraham unto Moses. To question a decision to locate London's airport made in the deep mists of time is to those in Whitehall simply unthinkable. However, the good news is that common sense did eventually prevail with Eurostar. After buidling the expensive white elephant that was Waterloo International because traditionally the boat trains from decades before came into south London, finally common sense prevailed as it should have done in the early 90s and we got the new St Pancras terminal. We need transport planners who can think well outside the box.

Mark, Sevenoaks, Kent

A great idea. We are too small an island not to reclaim land for a new major airport. It would help solve so many problems.

Anthony, London,

Heathrow is a monument to compromise. By repeatedly stifling expansion plans, London now has 3 major airports instead of 1, and they're all pretty poor by international standards, with Heathrow amongst the worst. The world will be arriving for the Olympics in 2012, and they'll be better served by arriving in Paris and getting on a train... What a fiasco.

John Beecroft, Camarillo, CA, USA

Very popular idea in south west and west London, where we are deafened.

Richard Tracey, Wandsworth, London,

Heathrow is totally run down, but bit of development work should spruce it up..

I think jus saying 'relocate' an airport is simplifying things a bit. Heathrow is MASSIVE. there are hundreds of supports companies, warehouses, logistics etcetra

I do think we should build another clean fresh airport with multiple runways that has the potential to become the super airport.. and let this airport have much cheaper and more available landing slots etcera to attract airlines.
But not close heathrow down. heathrow will probably experiance a decline in flights.. or at least the new airport could pick up the slack.
I suppose there is always the issue of it becoming a pointless like gatwick. Ca'nt gatwick build another runway? or same issues as heathrow

Of course the established airlines would say no to a new aiport- they own expensive landing slots whose worth would be devalued.

chetas, croydon, surrey

hong kong spent 20billion on an entire airport?...and 11billion to build the Thames Reach project ....and "officials" claim it will cost 13billion on a runway????? is someone "offcial" taking the piss here ??

that aside , heathrow is a dead duck.. the cost of building in essex would be underwritten by the profits earnd by the re-development of the old and prime located sight. Money-wise there is not coherent argument against re-location.. one accident, one act of terrorism and we face a catastrpohe in our capital - if we can avoid that at minimal cost then for that reason alone we should argue that London deserves safer airspace.

zugerman, zurich, switzerland

Rather to my surprise, I'm gradually coming round to the idea of Boris for Mayor.

Barry, Wallington, UK

As a resident of Gravesend I strongly support the building of an airport at Cliffe. Heathrow is a nightmare with flight paths that are a potential threat to thousands of households. Cliffe is a wasteland (purported to be a very important birdstopping place during migration - but they would find somewhere
else!) and an environmentally suitable situation ifor transport accessibility - it could be fed from north of the river (avoiding congestion in Kent) as well as the south, with easy access to the high speed rail link to the continent without the problem of flightpath nuisance. It is an obvious solution that would surely compansate for the job losses at Heathrow and its creation would encourage the development of a presently poor area.

Colin Bedwell, Gravesend,

There already is a huge runway in north east kent. Its at an airfield called Manston.If you google Manston you can view the arrival and departure route currently used which is almost entirely over the sea. The north kent rail line is close and a major upgrade to allow initially say 6 high speed trains an hour into London would make it a similar proposition as the rail link from Gatwick or the underground to Heathrow.
So you could achieve the capacity of a third runway at Heathrow by upgrading the rail link and building a terminal.

Nigel Cottrell, Crowborough, East Sussex

I'm with Boris. Heathrow is the most unpleasant airport I have ever used. It is a sprawling monstrosity, inefficient and outdated. Gatwick is not much better, and is poorly located and connected for the majority of the population The time has come for a new "super" airport with capacity for efficient operation and not requiring travellers to face cramped conditions and extended hikes to get to and from flights - with 21st Century road and rail links to the main population centres of the country - not just London.
I'm sure that the current Heathrow site could provide much-needed "brownfield" development sites for homes - much to the relief of those of us having commuters inflicted upon us to relieve the housing shortage in London - much to the detriment of our local economies, creaking infrastructures and the environment.

Mark, KETTERING, England

I think it is time to replace Heathrow because it so obsolete and at operational capacity. Given that the U.S.-EU Open Skies Aviation Agreement goes into effect next month, Britain's busiest airport is not prepared to handle all the new transatlantic flights that U.S., British and European airlines want to fly now and 8 years into the future. London needs to build a new mega airport that has at least 6-7 runways with 24-hour flight operations and that any airline from around the world that wants to fly to Britain's national capital would be able to do so without going through the long hard hassle of securing runway slots and terminal space which now happens at old Heathrow. Other world cities such as Hong Kong and Seoul have built large new airports when their older airports became outdated and London risks being left behind unless it follows suit. Building a third runway at Heathrow will not solve the congestion problem and is nothing more than a Band-Aid solution.

Erik K. Weseman, Middlebury, USA, VT