[quote=The Nexerus]
The UK's position on a currency union between the United Kingdom and an independent Scotland is identical to their position on the United Kingdom using the Euro. To quote the head of the Bank of England verbatim, "A currency union is incompatible with sovereignty."
[/quote]

Again, these are nice words. But it's a political move. Westminister has a duty to keep it's economy running, and if it didn't make a currency union with us. They're basically saying "We won't bail you out. But you can leave without any debt, still letting you use the pound anyway as we can't actually stop you, and if your country does fuck up, we'll lose our 2nd biggest trade partner and heavily ruin our economy as well".