If the tea-leaves are being read correctly, it looks as though the world is soon to embark on a co-ordinated fiscal expansion. The UK arm of this is already being talked about, with Mrs May having ditched George Osborne's impossible timetable for balancing the books before she even became PM. The economic situation really has changed since 2010, in that even in the post-referendum mini-paddy nobody has predicted that the UK's public finances are in danger of running out of control - which was a genuine worry in the late-Brown-early-Cameron era.
The politics has certainly changed. While it is lazy to read general themes from the referendum numbers, it seems that a lot of people may have voted Leave because they were frustrated by economic stasis and they wanted to give The Establishment a black eye for having let things slide; and at least some of that is thanks to the big fiscal squeeze under George Osborne*. A more balanced UK economy is going to require some big investments. Not all of that has to be led by the public sector, but it seems inevitable that not all of it can or ought to be privately-financed.
BUT. One of the most important criticisms of public-sector investment is that it is so often misdirected. This is hugely important, because the efficient allocation of capital is the be-all and end-all of successful economic policy. Building the feted "roads to nowhere" takes capital away from the productive sector and allocates it less efficiently.
So how might we work out how to decide how much to spend and, crucially, how to spend it?
With borrowing rates as low as they are, it makes sense to borrow big and borrow now. The world's holders of cash are running around in search of yield and security. The government could gain a bit of confidence from the markets by hiving off bonds for infrastructure investment from day-to-day spending: Gordon Brown's Golden Rule in certificate form...
But UK politicians are notorious bad at spending money sensibly. Pet projects, vanity projects, pork-barrelling and general incompetence rule OK. But we can take advantage of the re-emerging diversity of decision-making in Team UK. For example, should more money be invested in London infrastructure or would the same money be better spent Oop North? Let the super-cities, combined authorities and monkey-mayors compete for the cash. In other words, auction the cash. Run competitions. Use tested multiplier formulas. Hold these local governments' accountability to the fire by making the availability of funds contingent of the area's ability to raise additional tax revenue. In other words, let a million projects be proposed, and only push the button on the best of them.
The buck will, of course, eventually stop at Westminster and its national tax-raising abilities, but we should avoid giving Whitehall itself the chance to go on a white-elephant binge. We can do better than that.
Also, the UK government should immediately give a decision on airport expansion in the South East. This should be relatively easy in the new political and economic environment. The simple answer is this: to give BOTH Heathrow and Gatwick permission to build new runways, but stating that the taxpayer's contribution to consequential transport upgrades will be auctioned off. Let the two airports effectively bid to take the least amount of public cash.
* a wooden spoon prize to the first, second and third commenters who claim we have not had a fiscal squeeze in the UK. Please go and read David Smith.