Even after Boris Johnson stops being Mayor of London, he will never abandon the idea of building a great new airport east of London. So says his aviation adviser, Daniel Moylan: “Boris will go to his grave believing this is the right thing to do, or to have done. I’m absolutely convinced of that.”

To the outside world, the campaign for an airport in the Thames estuary – popularly known as Boris Island – may seem sunk. The Davies Commission has dismissed the proposal, and insists the choice is between building a new runway at either Heathrow or Gatwick. Those two airports are now pouring vast sums of money into advertising campaigns designed to make one or other of them seem the natural choice.

But Moylan insists the fight is not over: “Boris thinks, and I think, there will be another opportunity when Davies reports.” That will be after the 2015 general election, for the politics of this decision are so alarming that the powers that be have decided to keep the voters as far away from it as possible.

Boris and Moylan have no advertising budget. What they possess are brains, and the independence of mind needed to see where the argument goes.

Moylan is at pains to stress that Boris is not just motivated by opposition to building another runway at Heathrow: “I think his character is not comfortable with being in pure opposition. If Boris disagrees with something, he could attack it, and indeed sometimes he does attack it. But he’s not wholly comfortable being solely in the attack mode. What he wants to do is find a better answer. So it isn’t enough for Boris to say Heathrow can’t expand. He’s got to find a solution, and a solution that works for London.”

Moylan contends that in order to thrive, London must have a hub airport with more capacity than will ever be tolerated at Heathrow: “If Heathrow’s right that Heathrow needs to expand – and in a sense they are right – but if it is politically undeliverable and environmentally wholly barbarous, then it doesn’t require the genius of a Boris Johnson to work out that Heathrow should expand on a different site. And Boris put through two proposals to the Davies Commission with equal vigour. One was an estuary proposal and one was Stansted.”

ConHome: “Given the cogency of the case that you and Boris have made, why do you have so few allies?”

Moylan: “Well, I ask myself that question. I take some small comfort in asking myself the same question in connection with Gatwick. Gatwick are doing extremely well. As a spectator, I applaud what Gatwick has done. They’ve taken a very poor case and made a very good fist of it. But have you noticed, nobody supports Gatwick at all. They have no supporters. Even their principal airline has come out against it. EasyJet. They struggle on without any support, with cheery optimism, and Davies leaves them in the frame.”

ConHome: “But why are Boris and yourself not in the frame?”

Moylan: “I think the problem is at Heathrow. There are two things one could say about this. One is quasi-Marxist. Heathrow is there, and a lot of people think it’s just easier to do something that’s there. Actually, it isn’t always easier to do something that’s there. Trying to ram yet another extension into your house may actually be more complicated than just selling up and buying a new one.

“But the other thing is that Heathrow is, and this is quite well documented going back to the 1960s, part of a power nexus, it’s a sort of aviation-industrial complex that goes back to the time when Heathrow itself, and British Airways, were arms of the state, when you had the Department of Transport and the Civil Aviation Authority and British Airways and the British Airports Authority all just arms of the state, and they genuinely decided what needed to be done, and of course there were public inquiries and so on, but all these had to be defeated.”

ConHome: “So your allies get nobbled by this corporate nexus.”

Moylan: “Yes, which draws in the CBI and the nay-sayers and the gloomsters. It’s amazing that Davies takes almost no cognisance of what’s happening in other parts of the world in his ruminations. It’s this island mentality. The fact that it is basically British engineers and British architects who are building these foreign airports means we have the expertise. What we lack, apart from Boris, is the vision.”

ConHome: “Well, why have the Chancellor and the Prime Minister been seduced?”

Moylan: “The interesting thing about the Conservative Party in the lead up to the 2010 election is the fact that policy-making was quite devolved. So the Conservatives decided in the run-up to the election that they wouldn’t support what was then Government policy of a third runway at Heathrow. The Liberals of course would never have supported it. So when the coalition was put into place that was an easy brick to nail down, and they in fact embellished it, and said no more runways at Heathrow, Gatwick or Stansted, which is the Liberal demand. So trying not to talk about airports and runways for five years became rather more attractive than having a solution. But the difficulty was that you already had Boris out there, batting for this, and they hadn’t taken account of that in the coalition agreement, in those peculiar discussions going on in the Cabinet Office. Boris was not present. Perhaps he should have been.”

Moylan reiterated the case for Boris’s approach: “If you had an airport on the east of the capital, or even at Stansted, you would create a huge pole of activity which would create jobs and transport, which would open up land for housing, it’s magnificently the right thing to do. And then you’d be left with the Heathrow site, which is the size of Kensington and Chelsea as a borough, slightly larger, with reasonably good transport, and you could actually develop a new London borough, a whole new town on the Heathrow site. Now Sir Peter Hall, not the theatre director but the geographer, who died a few months ago, was battling for this for 50 years.”

ConHome: “So we’ve got an aviation-industrial complex.”

Moylan: “The Department for Transport is the least important part of that now. They’ve given up trying to have a policy. The Treasury is much more important.”

ConHome: “So Davies is really just a talking shop. Or is it in fact a way of doing Heathrow?”

Moylan: “Well I don’t know what Davies is going to say because I don’t think Davies knows what he’s going to say. I think he’s said publicly he’s going to write his report after the election.”

ConHome: “But he’s boxed himself in.”

Moylan: “I think it’s very foolish from his point of view that he’s boxed himself in to a choice between one answer which is politically and environmentally very very difficult, and another answer which is not the right answer to the exam question, and most of the aviation industry and business more generally would say that’s not the answer. It’s not the case that airlines are going to shift from Heathrow to Gatwick. Willie Walsh [the head of British Airways] wants to have the whole of Heathrow to himself.

“Willie Walsh’s position on this, on the one hand it’s hard to criticise, on the other hand it’s just sad. What he says is, no one in this country is ever going to do anything about this, so I’ll carry on running my business. Of course Heathrow should have four runways, it’ll never happen, so I’ll carry on running my business. On the one hand it’s realistic, so it’s hard to criticise, on the other hand it is I think tragic that the main airline in this country has opted out of serious debate about the future of airports in this country.”

Moylan posited the economic motive behind the defence of Heathrow: “This is not about capitalism. This is not about business. This is about private monopoly behaviour. Monopoly seeks to restrict supply. Monopoly is comfortable with an airport that is small. Monopoly wants to expand at exactly that rate that will ensure it never has any spare capacity. You have to understand their behaviour in that light.”

ConHome: “It’s been possible for many years to defer building a new runway, but UKIP is a more immediate problem. How should the Conservatives be addressing it?”

Moylan: “That is a question of leadership and personality and character and credibility. Nobody ever says, ‘This is the sort of Britain I think we should live in.’ I think Boris has more of that than most. You can throw together a Boris world.”

ConHome: “Could you just do that?”

Moylan: “The first thing about it is it’s optimistic. It’s a world in which you can actually achieve things. It’s not a nay-saying world. The second thing is it’s a world in which people are not interfered with. It’s a socially liberal sort of world. It is a world in which people who come to this country and strive and do well are thought of as being on the whole a good thing rather than a bad. So many of us are immigrants. My family is an immigrant family.”

Moylan’s mother was from County Clare, his father from County Galway. They met and he was brought up in Birmingham: “I understand people who grow up in households where the word ‘home’ means a foreign country.”

Moylan himself was President of the Oxford Union just before Alan Duncan, and a few terms after Damian Green. He has served since 1990 as a Conservative councillor in Kensington and Chelsea, and since 2008 as a director of Transport for London. A film can be seen on YouTube of Moylan introducing a lecture at the Union by Richard Nixon in 1978: Nixon begins by saying with a grin that the demonstrators who can be heard chanting against him outside “have made me feel very much at home”. But Moylan’s own political heroes are Ronald Reagan and Margaret Thatcher: two leaders who opposed the prevailing wisdom about what was achievable, and overturned it.