Vaulting Victorian ambition conquers common sense My airport is bigger than your airport. My airport will, at least, be bigger than your airport in 15 or 20 years" time, once I have got it built. And after a similar period of time has elapsed, my train to Birmingham will be faster than your train to Birmingham. The government has begun to display a Victorian enthusiasm for grand feats of engineering. Daniel Moylan, who advises Boris Johnson, London's mayor, on aviation and is deputy chairman of Transport for London, says of the plan for a new airport in the Thames estuary: "This is transformative. Its effects will still be felt in 500 years" time." Three years ago, when Mr Johnson chugged out into the estuary on a dredger loaded with engineers and journalists, the idea struck most people as a fantasy. Boris Island was far too expensive and difficult to be realistic. We would need, in the usual British way, to make do and mend what we already had, namely Heathrow. But Heathrow proved even more unrealistic. Mending it by building a third runway turned out to be a political impossibility. So once everyone had got over their feelings of bereavement, and had accepted that a planning blunder of the 1940s could not be turned into a world-class airport for the 21st century, they began to realise that the estuary might after all be the only chance for London to compete with Amsterdam, Paris and Frankfurt. In the 1960s London failed to modernise its docks because it was all too difficult and, in response, trade went to Rotterdam. Were we now going to see a similar failure of nerve? Was the new airport going to be, like the Channel Tunnel, a project that would take a century to come to fruition? Then opinion began to shift. The dangers of sitting tight and tinkering with the airports we already possess started to seem greater than the dangers of building a new hub east of London: a new front door to the world. Tinkering stands in a not very glorious British tradition. It is what we have generally done with our mainline railways. Andrew Adonis resolved, during his brief spell as Labour's last transport secretary, that this was not good enough. Alistair Darling has described how in the summer of 2009, Lord Adonis made the case in cabinet for a new generation of high-speed trains. Mr Darling, who had spent four years as transport secretary before becoming chancellor, took a morose view of the subject: "Whether or not a high-speed train will ever get north of the English Midlands - if, indeed, it is built at all - I don't know. Maintaining the present network is tough enough. That is always one of the most plausible arguments against doing anything bold: that the struggle to fulfil existing commitments leaves no spare capital. But even the cautious Mr Darling could see the huge political merits of Lord Adonis's initiative: "Andrew's boyish exuberance and serious intent rekindled the fire that any government needs - particularly one like ours." And there we see the motive that impels David Cameron and George Osborne to sanction the building of the high-speed line to Birmingham: an enormously expensive project that only makes sense if further billions are spent extending the line to points further north. To do something like this is to give emphatic proof not just of one's exuberance, but of one's modernity. There are strong arguments against the HS2 project. Getting to Birmingham a few minutes quicker does not justify the exorbitant cost of the new line, or the damage it will do to the Chiltern Hills. For that sort of money we could make any number of less glamorous but more worthwhile improvements to the network we already possess. Also, a slower journey to Birmingham, during which one has the time to read a book, eat a meal or work on an electronic device, is in many ways preferable. However, now that the government has thrown its weight behind the plan, opponents are in danger of being dismissed as a group of reactionaries who have decided, out of pure selfishness or cowardice, or ignorance of modern needs, to stand in the way of progress. The building of the new railway becomes a declaration of confidence in the future, while to oppose it is to show that one would rather live in the past. From a political point of view, vaulting ambition is much easier to defend than purblind timidity. Mr Johnson admits that in the end it is for the national government to decide whether to go ahead with the estuary airport. But he observes that this is a question not of money but of political will. By saying this, he has made the airport a test of Mr Cameron and Mr Osborne's virility. Are they strong enough to uphold London and the UK's competitiveness, or are they a pair of weaklings who will collude in national decline? The mayor of London much enjoys teasing Mr Cameron and Mr Osborne by saying things they would never dare say. On subjects as varied as cutting the top rate of income tax and encouraging the Greeks to reintroduce the drachma, Mr Johnson has mocked the caution of his friends at Westminster, and they know they can expect to be shown up as wimps if they bottle out of agreeing to a brave new airport in the estuary. We cannot yet be sure, but Mr Cameron and Mr Osborne appear to be in the process of asserting that they are every bit as virile as Mr Johnson. The role of weakling is left to Nick Clegg, who opposes the new airport. The prime minister and chancellor appear confident enough to press ahead, just as they pressed ahead with HS2. In a paradoxical way, the opposition they meet from local Tories who are aghast at the desecration of the Chilterns makes the new railway more attractive, for it shows that the government will not yield to private sectional interests, even when these are voiced by such a well-connected Nimby as William Astor, who happens to be Mr Cameron's stepfather-in-law. The grandeur of the plans for a new airport and railway makes them good politics, because people who decline to support these big ideas can be made to look small. My ambitions are bigger than your ambitions. I have a vision, while you think we can muddle through. I am a leader, and you are just going to have to follow me. The writer is the author of "Boris - the Rise of Boris Johnson"