As we all know, knowledge is local and dispersed. A corollary of this is that you, the readers collectively, will always know more on any specific subject than one single writer on this side of the software. At which point to ask you a question. We've got the BBC telling us that public spending is going to fall to levels not seen since the 1930s. This does seem unlikely: although if we could get government back to the sort of levels of interference in our lives of the 1930s that would be both nice and an achievement.

The Office for Budget Responsibility (OBR) says spending on public services is heading for an 80-year low.

In its report accompanying the Autumn Statement, it projected that spending by central government on public services was going to fall from 21.2% of gross domestic product (GDP) in 2009-10 to 12.6% in 2019-20.

As a proportion of GDP, that would probably take spending on public services to its lowest since the 1930s.

That report is here.

Note that this isn't public spending as a whole: this is nothing to do with pensions or the welfare state or other transfer payments. This is solely what is spent upon public services, not money shuffled from one citizen to another.

And the question is, how important is that word "central" in that calculation?

For example, just imagine we moved NHS funding from its current system to the Swedish or Danish one? There it is, respectively, the counties and the communes that raise and spend the taxation that pays for the health care systems. That money simply doesn't flow through the national treasury nor the central government (which is why Denmark's standard national income tax rate is 3.76% and the top one 15%). We can all think of reasons why this might be better (local accountability, greater efficiency) and possibly some that it might be worse (postcode lottery!). But it's not obvious that there's either less or more government spending on public services in either system: but there's obviously a huge difference (as much as 10% of GDP) in central government spending.

So, of this reduction in central government spending on public services how much is a reduction in government spending on public services and how much is just the movement from central to some other level of government spending?

We could argue that the Scottish and Welsh NHSs, for example, are covered by the Parliament and the Assembly, therefore aren't any longer central government. There's a change coming in the allocation of business rates. As was these were all collected centrally and then apportioned. The new system will see some being retained locally and spent locally: if that a reduction in central spending but not in public spending? As things become devolved do they fall out of central spending but still remain public spending?

In other words, how much of this reduction is not really a reduction, just changes in the budgets that the spending is coming from?

Over to you: and let there be more light than heat.