Under-promise and over-deliver is a good rule for politics (and indeed, for other walks of life) – pleasant surprises are always welcome. Unfortunately, the reverse is all too common – particularly when it comes to government infrastructure projects.

It is six years since the TaxPayers’ Alliance first calculated that major capital projects tend to go 38 per cent over budget on average. Things have improved somewhat since the demise of Labour, and its fetish for big databases, big gimmicks and big budgets. The Coalition certainly made some improvements, reviewing a variety of projects in order to rescue, scale back or cancel them as appropriate.

But as Patrick McLoughlin could tell you, the problem is still not solved. The latest news that £38 billion of rail improvements has been put on hold (because Network Rail wildly over-promised on its capacity to deliver them) is troubling and frustrating in itself. Sizeable amounts of money may already have been wasted, and rail passengers who have spent years waiting for upgrades face yet more delays.

Further evidence of the disease can be found in the latest update from the Major Projects Authority. The Times reports that:

‘One in four of the government’s biggest projects is in danger of failing, including an army recruitment scheme and a programme to bring back and rehouse troops from Germany. A report from the government’s Major Projects Authority said that of 188 large projects worth £498 billion, 49 were either unachievable or needed urgent changes. Eight projects were given the highest “red” category including five health schemes, two defence programmes and one from the Ministry of Justice, while a further 41, including high-speed rail and universal credit, were assessed as “amber-red”.’

It seems the public sector is still struggling to deliver large-scale capital projects in general, and finds rail developments particularly difficult.

All of which raises serious questions about the biggest of the Government’s capital projects: HS2. Keen readers will remember that the ConHome Manifesto suggested HS2 should be cancelled and the money used to benefit the North of England in other, more effective, ways.

The debate around the new High Speed rail network focused almost entirely on whether it was desirable. Recent developments suggest that the real question is whether it is feasible.