Something of a breakthrough has happened, with Tony Blair labelling support for independence as being "self-indulgent". He was speaking about Sir George Mathewson's support for the SNP in the coming elections and his backing for Alex Salmond as the "outstanding" candidate for First Minister.
Sir George is regarded as the driving force behind the Royal Bank of Scotland's rise to being one of the biggest financial institutions in the world today. Bizarrely, Blair sought to deflect his position by saying that Sir George's view was not that of "real businesses". Not a good day for the speech writer.
But for me, the strangest part of the prime minister's response was to characterise it as being "self-indulgent". Unionist politicians have never seen any benefit to independence, but the prime minister's comments betray that there must be something to it now. Even if he was claiming selfishness of the part of Sir George, it would be safe to assume that others would also be similarly placed to benefit.
I suspect though that we are talking about self-indulgence in the broad sense. The kind of self-indulgence we're told that Scots would be engaging in if they kept all the oil wealth to themselves, as if it is normal for nations to go sharing their natural resources with others, much less have someone else "look after" it for them.
The mood within the SNP at the moment is understandably buoyant. Sir George's intervention marks something of a watershed:
"I do not share the fear of independence which is currently being fostered by those who have most to lose by a change in the status quo and those who see Scotland as a source of safe seats thus guaranteeing their rule over the UK."
Top business chiefs have never socked it to Labour in this way, with all the patronage and influence that came from a cosy relationship. This is the latest in a line of such figures who have been converted to the independence cause, and it is not surprisingly being taken as a sign of power slipping away.