No news is good news - if you're the SNP, that is. And the latest poll from Scotland shows very little change at all - the SNP still top of the heap on 46 per cent, Labour a distant second on 27 per cent, the Conservatives in third place on 18 per cent and the also-rans knocking around in the low single digits. Small wonder that our sister site, May 2015 projects the SNP to take all but one of Labour's 41 seats in Scotland.

It may be worse for Labour than even the headline figures suggest. The polls fluctuate a little, but effectively what it reveals is that public opinion in Scotland remains where it was: 45 per cent for independence and 55 per cent against. That vote share - 45 per cent - is obviously insufficient in a referendum but devastating to Labour under first past the post (and little better in the D'Hondt system favoured at the elections to the devolved parliament). "You cannot fight an idea," as one shadow Cabinet minister is fond of saying, "Except with a better idea." Fairly or unfairly, Labour in Scotland, like in England and Wales, is seen as having little in the way of fresh ideas.

But it seems unlikely that a change at the top, either in Scotland or the United Kingdom as a whole, is unlikely to benefit Labour. The polling suggests that not only do the SNP's supporters want to live in another country - increasingly as far as their opinions are concerned, they already do. Take Jim Murphy's approval ratings, not stellar but around the David Cameron mark at -10% in the latest publically avaialble poll. But that conceals strong ratings among Labour voters (+55 per cent), Liberal voters (+13 per cent) and Conservatives (+ 5 per cent). (To give you an idea of how good those are, Cameron is at -71 per cent with Labour voters in the rest of the UK.)

But among SNP supporters Murphy's polling is terrible, at -54 per cent. And just as Ukip voters split from the country at large on issues ranging from the large - they are more likely to believe that they will see the apocalypse in their own lifetimes - to the small - they believe that Sean Bean should play Nigel Farage in a movie, while everyone else favours Rowan Atkinson - SNP voters have broken away from all other voters. I'm told that there will be detailed polling on the impact of the Scottish goverment's review of government expenditure and revenue (GERS) soon. The government's figures are fairly devastating for the case for independence, but in private sampling and on the doorstep, as with public polling on the oil price, the SNP's supporters are reaching radically different conclusions than the supporters of the Unionist parties.

It seems likely that there is no policy offer that can pull away a significant chunk of that 45% that is currently allowing the SNP to sweep all before it. Labour's woes still have a way left to run.

(I've notably avoided the Greens because the polling evidence is so scarce. Both Labour and Green campaigners in Scotland report that the boost in that party's standing seems to have less to do with independence - "that RIC-SSP-Trot block, it's joined the SNP not the Greens" in the words of one - and more to do with the overall Green surge. But with no public opinion polling specifically on the Greens and seemingly little private data either it's really all supposition.)