If you wanted to present one iconic example of the kind of extravagant folly that demonstrates the stupidity, verging on certifiable lunacy, that afflicts those who govern us, you could not ask for a more powerful illustration than the aberration that is the High Speed Rail Link from London to Birmingham (HS2).

It has been with us for a decade, though only on paper, and the evolution even of that notional project should have alerted any sane individual to the fact it made the South Sea Bubble and the Groundnuts Scheme look like attractive propositions. It began in 2007 as a proposal by Greengauge 21, a transport industry lobby group, with an estimated cost of £7.1bn.

In 2009 Gordon Brown’s Labour government, looking for Blair-style projects to serve as virility symbols, announced the creation of HS2 Ltd to develop this excrescence. By 2010, when it had acquired the additional toxicity of an environment-destroying route through the Chilterns, the cost had risen to £30bn. At the end of 2010 the Coalition government amputated the proposed spur to Heathrow, but reaffirmed the project. By 2013 the cost had risen to £42.6bn and even Peter Mandelson, one of its original sponsors, denounced HS2 as an “expensive mistake”.

In May 2013 the National Audit Office said the benefits of HS2 were “unclear” and the timetable “over-ambitious”. Simultaneously, the Major Projects Authority graded HS2 “amber-red” – at serious risk of failure. In March 2016 research revealed that the track could break up and trains derail at the proposed speeds, the highest in the world. This appeared to excite the heroes on the slime-green benches at Westminster, since the House of Commons’ response was to pass the HS2 Bill.

By 2015 the alleged cost had reached £55.7bn which, like all such assessments, was almost certainly an underestimate. The original pretext for visiting this disaster upon the public had been the imperative need to transport businessmen from London to Birmingham 30 minutes faster. This ignored the modern reality that contemporary businessmen do more serious work on their laptops aboard trains than at hot-air meetings. Since the speed thesis was falling apart it was replaced by the claim of extra capacity (now also discredited).

In July 2016 the new post-Brexit Transport Secretary, Chris Grayling, committed himself to continuing HS2. Two months later HS2 chief executive Simon Kirby, despite his £750,000 annual pay packet, resigned to move to Rolls-Royce. That looks like a seriously wise career move by him. It is dawning on more and more people in the north that, so far from carrying enterprise from London to northern cities, HS2 will suck even more commercial activity southwards to London.

In the meantime it is a squanderfest, having cost the taxpayer £1.4bn already, with not a rail laid yet. Last summer the Taxpayers’ Alliance published a report entitled “Rich man’s toy: The case for scrapping HS2”, which deconstructed the purely imaginary case for this madness. It pointed out that projected costs are rising and were likely to reach almost £90bn, that turning Birmingham into an outpost of London was a bad idea and that technological developments such as autonomous vehicles will make HS2 an obsolete technology long before it opens.

Only one of the many forceful arguments advanced by the Taxpayers’ Alliance is unconvincing: the claim that eventual costs will total £90bn. That is a hopelessly optimistic assessment. Vanity projects such as HS2 notoriously fail to complete within anything like their projected timescale and their costs have a propensity to increase at a pace resembling arithmetic progression. Expenditure on HS2 rose by a third in 2015 alone.

HS2 is due to be completed in 2033 – 17 years from now – and if it conforms to previous vanity projects will significantly overrun that target date. Effectively, we are looking at the prospect of two decades of serial blunders, unforeseen problems, the whole gamut of long-term hazards that invariably put such projects into fiscal freefall. By the time HS2 has negotiated the innumerable legal, political, geological, logistical, environmental and managerial perils, to emerge into a future society where it will be as contemporary and relevant as Stephenson’s Rocket, £90bn will be small change compared to its final cost.

Yet the landscape is to be raped, communities bulldozed, house prices on the route destroyed and the lives of many thousands of people reduced to misery. Why? We all know why, in this post-referendum, post Trump election era. Because the establishment has decreed it shall be so, as it has throughout the lifetimes of everyone alive today. You could not ask for a more representative example of an elite project than HS2. Until very recently, that would have guaranteed its inevitability.

Today and in the years immediately to come, the unmistakably arrogant imprint of the establishment on HS2 may have the opposite effect. There is a new mood of self-liberation among the British people and the spectacle of their hard-earned money being squandered in shed-loads on a project that an intelligent schoolchild could see is ludicrous may yet trigger a rebellion.

It is sensible, on the eve of Brexit negotiations and the temporary instability that may accompany them to steward our money wisely. The fantasist claim in 2012 that HS2 would “create a million jobs” was proof only of the contempt in which the establishment held the public’s intelligence. We live now in changed days when politicians can expect to be held ever more strictly to account by the electorate. In that climate a Soviet-style vanity project designed only to glorify the political class is a downright provocation.

The recent change in Britain’s political culture, post-referendum, has at last given the absurd HS2 scheme a serious purpose: to serve as a litmus test of how far Government has adjusted to reality, how far it is in touch with public opinion and whether, with the Government spending £784bn this fiscal year and the national debt running at £1.64 trillion, the state has got into the casual, addictive habit of spending too much of citizens’ money. Beyond that, scrapping or retaining HS2 amounts to a test of sanity.