The latest TNS BMRB monthly poll of referendum voting intentions is published today. However, it was conducted between 20th and 27th November, largely before the publication of the White Paper on the 26th November. The poll thus does not take us any further forward in ascertaining whether the launch of the White Paper has had any material impact on public opinion.

Still it is of some interest. At first glance it provides yet further evidence that the balance of opinion remains remarkably stable.  At 26%, support for Yes is up on last month’s reading by just one point, while the No tally is down by the same miniscule amount. Such small differences may be no more than a reflection of the random variation to which all polls are subject.

However, if we look at the complete run of polls that TNS BMRB have conducted this autumn – as we do in the table below – we uncover an interesting trend. Slowly but surely the No vote has been edging down. Each drop from one month to the next has been small and seemingly inconsequential. But over the four month period as a whole the monthly changes have cumulated into a five point drop in No support, mostly as a result of an increase in Don’t Knows.

Here perhaps is the first piece of evidence from published polls to lend some support to the Yes side’s oft repeated claim that their efforts at canvassing and talking to voters are persuading people to shift from No to undecided – and thus perhaps eventually become potential Yes voters. It certainly suggests that Alistair Carmichael, the Scottish Secretary, was right to warn his Cabinet colleagues recently that victory for the No side is not assured.

But we should not push this argument too far. Once we take the Don’t Knows out of the calculation the latest poll points to a 38% vote for Yes, 62% for No, as compared with 35% and 65% respectively in August. However, when TNS BMRB first polled people’s referendum vote intentions back in February they registered a 39% Yes vote. So perhaps all that can be safely said is that Yes support is somewhat higher now than it was in a poll in August that produced a particularly low Yes vote. Moreover it was a poll that was criticised for containing more people who said they had voted Labour in 2011 than said they voted SNP  – a potential problem that has since lead TNS BMRB to weight their polls so that how people say they voted in 2011 matches the actual result.

One other useful feature of TNS BMRB’s polls is that since August they have reported how people say they will vote broken down by the Scottish Parliament region in which they live. No individual poll contains enough people in each of the regions to give us anything like a robust estimate of the size of the Yes and No votes. But between them the four polls have interviewed some 500 or so people in each region, so if we join the four polls together we can secure an estimate in which we can begin to have some confidence. With the Don’t Knows removed, this is the picture that emerges:

                                                % Yes
Highlands & Islands                 39
North East                                37
Mid Scotland & Fife                 29
Lothians                                   41
Central                                     37
Glasgow                                  37
West                                        38
South                                       34

It appears that for the most part support for independence does not vary a great deal from one part of Scotland to another. There is certainly no evidence that the SNP’s particular strength in the North East is reflected in a higher level of support for independence there. The only marked departure from the general mood of the nation seems to be a particularly low level of support for independence in Mid Scotland & Fife – though quite why this should be the case is not clear.  It may perhaps be no more than a quirk of the character of the particular places in which TNS BMRB’s polls are being conducted in that part of Scotland. In any event, the challenge facing the Yes side is evidently Scotland wide, not confined to one particular part of the nation.

About the author

John Curtice is Professor of Politics at Strathclyde University, Senior Research Fellow at ScotCen and at 'UK in a Changing Europe', and Chief Commentator on the What Scotland Thinks website.