There have been a lot of contradictory suggestions about what "the main lesson" of the new TNS-BMRB referendum poll is, but to my mind the most important lesson is that when the No campaign crow about a poll in advance, it's no longer safe to automatically conclude that the No lead must have increased, or even remained static. With the TNS datasets having been released on Tom Hunter's website, we now know that the No lead has in fact fallen by 0.6% after undecideds are stripped out.
Should Scotland be an independent country?
Yes 41.4% (+0.3)
No 58.6% (-0.3)
41.4% is also (albeit only fractionally) a new high watermark for the Yes vote with TNS-BMRB in the campaign so far - the previous high was 41.3%.
Even on the headline numbers that take account of Don't Knows, it turns out that No have been heavily flattered in the published figures by the effect of rounding. Here is the position when rounding is only to one decimal place -
Yes 32.2% (+2.6)
No 45.6% (+3.2)
So the "widening of the gap" that the No campaign are wittering about (spin which one or two media outlets have stupidly - if predictably - fallen for hook, line and sinker) amounts to a statistically insignificant 0.6% - exactly the same amount by which the gap has narrowed on the more important measure that excludes undecideds.
The one silver lining I can see for No in this poll is that, in contrast to the last couple of TNS polls, respondents who say they are certain to vote are only very fractionally more likely to say they will vote Yes. However, the TNS figures after turnout filters are applied have tended to be much more volatile than the headline numbers, so not too much should be read into that. And the news is actually pretty good among respondents who say they are either certain or very likely to vote - the Yes vote among that group (with undecideds excluded) stands at 42.6%, which is very similar to last month's figure of 43.4%.
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In other polling news, the Tories once again seem to be standing on the brink of crossover in the GB-wide polls for next year's general election. The last couple of YouGov polls have shown Labour's lead shrink to just 1 and 2 points respectively. What will be the implications for the referendum if it becomes unambiguously clear over the next few weeks that David Cameron is heading for another five years in Downing Street? I think we can all hazard a guess...