As my colleague George Eaton wrote this morning, the political top-line from the government's announcement of a £50bn infrastructure program is that it signals a gruff acceptance of Keynesian economics :
The delusion that the coalition's spending cuts would increase consumer confidence and produce a self-sustaining private-sector-led recovery has been abandoned after Osborne's "expansionary fiscal contraction" turned out to be, well, contractionary.
But getting wonkish about it, there is something interesting buried in all this about how the government has chosen to execute this volte-face. Rather than simply borrow the money – at interest rates so low that it would basically be paid to do so  – it has announced that it will guarantee the private loans of any company which fulfils certain requirements.
Doubtless part of the reason is political. This way, the government can confidently state that they aren't adding anything to the deficit, even though this way of borrowing is functionally identical  to doing it the standard, on-the-books way. But part of it will be because infrastructure investment is really hard.
According to the FT:
To qualify for the new guarantees, projects must be ready to start in the 12 months from the offer being made and Treasury officials say they will be monitored to ensure they would not have gone ahead in any case.
The thing is, there just aren't that many shovel-ready projects simply lying around the place, and certainly not big flashy ones. Although the government is proclaiming that the Thames tunnel, the Mersey Gateway toll bridge and the A14 road widening in Cambridge could all be helped with the money, it's usually more mundane things which are the easiest use of infrastructure spending. Forget high-speed rail and airport islands, and focus on sewers and road resurfacing.
Unfortunately, its relatively tricky to spend £50bn on sewers in a year. Thames Water is replacing all the Victorian Water mains in London, but its taking 5 years and costing £5bn. To do it any faster would risk chaos in the streets. And noteably, they had already started that program without the governments money. That's going to be true of a lot of the low-level infrastructure investments that would otherwise be ripe for targeted spending.
So the government needs ideas. And what better way to get them than to offload the generating of them to the private sector? It's no longer just a government outsourcing based on ideology. It's now a government outsourcing because it has literally no idea how to enact policy it desperately wants to.
Osborne knows what it means to be Keynesian, but doesn't know how to do it. If you think you do, why not bid for his money?