THE UK has a lovely embassy in Paris.

Really lovely. It's an ornate former palace on the Rue du Faubourg St Honore, close to the Champs Elysee, complete with impressive gardens and that British diplomatic must-have, an ability to irritate the French, who absolutely refuse to accept it is grander than their own presidential Elysee Palace. The ballroom, where Rod Stewart played a gig last week, is particularly nice. At a rough estimate it's worth, oh, mega-squillions.

The SNP insists an independent Scotland would be entitled to, for the sake of argument and in very round numbers, a tenth of it. But how, in practical terms, the right to a fair share of the British embassy would be converted into providing the diplomatic functions required by an independent Scotland in France is unclear. Could the government of a newly-independent Scotland negotiate to work from Rue du Faubourg St Honore? Or would it seek a cash settlement from the UK to establish a new embassy? It wouldn't be too shabby, by the way. Grabbing a tenth of the British embassy would not mean down-sizing to the outer suburbs.

The vexed question of independence start-up costs raised its head this week after Yes Scotland released their latest campaign video. The heavily promoted film claimed "initial start-up costs" would be met by saving £250 million on Trident and a further £50m from waving goodbye to Westminster. If casual viewers came away thinking the total start-up cost of an independent Scotland would be £300m, they may feel misled. Yes Scotland stressed the start-up costs to which they referred were very much "initial", the "early bills", as a spokesman put it, though exactly what they thought the £300m would pay for remained unexplained.

At worst the Yes Scotland claim was misleading, at best it was meaningless. But at least it focused attention on a hitherto under-explored corner of the independence debate: the division of UK assets.

The Paris embassy is but a gilded, chandalier-dripping example of the countless calculations that would have to be made. Britain has around 200 embassies overseas. It operates one of the biggest and most complex military machines in the world. In the Department for Work and Pensions it has a ministry which in 2011/12 distributed welfare payments totalling £158 billion, including £14bn in Scotland. The UK has good old HMRC to collect taxes and an alphabet soup of regulatory bodies including the DVLA (driving licences), the FCA (financial services), Ofcom (broadcasting), the CAA (civil aviation), the HFEA (embryology) and the NLC (national lottery).

If Scots vote Yes next year, the Scottish Government will either have to reproduce these functions or seek a deal to share them with the UK. Brand-new bodies would require new premises, desks and pencil sharpeners, which would all cost money. Even deals to share functions would not be cost-free; just look at the £40m bill for HMRC to set up new systems to collect the Scottish rate of income tax.

So what might the total bill be? Would Scotland's share of UK everything cover it, or might one-off start-up costs threaten funds currently used for doing things? How much might need to be borrowed to protect services? Might the UK simply dismiss the claims, in which case a newly independent Scotland would face an immense task but at least unencumbered by £9bn of national debt?

I have no idea what would happen but neither, it seems, has the Scottish Government. Officials stressed an independent Scotland's entitlement to a "fair share of UK assets" but repeatedly failed this week to come up with so much as a ball-park figure for start-up costs. In an attempt to reassure, a spokeswoman said: "Any one-off costs of transition would be completely outweighed by the benefits that would accrue to Scotland as a result of independence."

It's perhaps unfair to criticise ministers too much before their promised independence blueprint in November, which is expected to provide this kind of detail. But the questions will not go away. Dividing up common assets, if an independent Scotland and the UK could agree to do that, would not be beyond the wit of man – but common sense suggests it would not be a straightforward process.