If I was trying to get out from under the thumb of Britain, I would claim it was almost dried up.
If I was trying to stay part of the UK, I would claim there are gobs more oil there just waiting to be poked with a straw.
That would only make sense if England were prepared to invade to keep Scotland from leaving. Since a referendum in Scotland is how they're doing it, it makes sense to suggest that Scots can live like Norwegians if only they separate from the UK. And it is theoretically possible given that Scotland's population is 1/10 of England's. Norway isn't a big oil producer, but it doesn't have all many people over whom to divvy up the profits from oil extraction. Scotland produces half the oil and has roughly the same population. Between the fact that Scotland has more industry than Norway and the oil money (1/2 of Norway's) being divvied up across roughly the same number of people, I'd say Scotland will automatically see its per capita income shoot up.