Today sees the publication of a second poll to be conducted by TNS BMRB for Sir Tom Hunter’s scotlandseptember18.com website, the stated aim of which is to improve the quality of the referendum debate. Much of the poll is thus about people’s perceptions of the quality of that debate and whether they feel adequately informed to make a decision in September, but it contains material on vote intentions too.

Regular readers will be aware that so far TNS BMRB have tended to identify a much higher proportion of undecided voters than other pollsters, seemingly because they ask people what they intend to do in September rather than either what they would do now or what they think they will do on polling day. However, as 18 September comes into view, this difference of wording should make less of a difference. It looks as though this may now finally be happening.

The proportion of undecided voters has slipped in this poll by six points, to 22%, as compared with TNS BMRB’s previous (regular) poll conducted towards the end of May. However, this drop has not resulted in any change in the relative proportions of Yes and No voters.

The Yes tally is estimated at 32% while No are on 46%. That means Yes are up two on TNS BMRB’s previous poll, and No are up four. But once the Don’t Knows are excluded the Yes tally, at 41%, is utterly unchanged. In other words, it looks as though (assuming no other major movements have taken place) that undecided voters have begun to divide between Yes and No in much the same proportion as those who had already made up their minds.

For a campaign that according to some polls at least is still well behind, that will come as a disappointment. The Yes side must have hoped that it would make further progress in reducing the No lead as and when undecided voters started to make up their mind. While there is little indication in this poll of any decline in Yes support, as suggested by the two most recent polls from YouGov, there is certainly no sign of any momentum. Of the seven polls TNS BMRB have conducted so far this year, all but one of them has put Yes on 41% (and the single exception was a reading of 40%).

Not least of the reasons why the Yes side is apparently not making any further progress is that it is failing to make headway amongst those whose first preference is some form of devo max rather than independence or the status quo. This group is important for two reasons. First it is relatively large; according to this poll it now represents 39% of the Scottish electorate, up six points on TNS BMRB’s last reading in May. Second, previous polls have found devo max supporters to be more likely to say they were undecided – and with 27% of them still in that frame of mind, that remains the case in this poll.

However, amongst those supporters of devo max who do reckon they know what they will do in September, No voters outnumber Yes supporters by no less than eight to one in this poll. As a result, no less than 56% of No support comes from those whose first preference is more devolution (up from 40% in May).

Yet this support seems to have been secured despite rather than because of any success by the No campaign in getting across either the message that more powers for the Scottish Parliament are on the way anyway or the promise that these powers will be augmented even further in the wake of a No vote.

Just 31% of voters (including just 31% of the supporters of more devolution) claim to be aware that more powers are already on their way as a result of the 2012 Scotland Act, while only 23% (including 21% of those who want more devolution) say that they are aware of the plans for more devolution of at least one of the three main unionist parties. The poll goes on to suggest that in fact the No side might be able to extend its lead further if voters were more aware of the provisions of the 2012 Scotland Act, and especially so if they actually thought that there was a guarantee of more powers. In the case of the latter proposition, for example, twice as many undecided voters say they would be more likely to vote No if there were such a guarantee as said they would be more likely to vote Yes.

To win the votes of the supporters of more devolution it looks as though the Yes side are going to have to do much more than simply persuade them that their preference will not be realised in the event of a No vote. Rather, they will need to be persuaded too that independence itself is a good idea. And on that issue it might be noted, for example, that the supporters of devo max (82%) are just as likely as backers of the status quo (also 82%) to say that it is important to them that Scotland should continue to be ‘able to use the pound as part of a currency union with the rest of the UK’.

And what do voters make of the quality of the debate they have witnessed? Not a lot it seems. As many as 45% do not trust the pronouncements of either the Scottish Government or the UK government when it comes to the predictions of the economic consequences of independence. No less than 63% say they have stopped listening to the debate because ‘both sides just contradict each other’, while as many as 73% say that, given their different claims, it is hard to know which side to believe.

As a result it seems that the referendum campaign has done little to make voters feel more confident about the choice they will have to make in just over two months’ time. At 47% the proportion who feel they have enough knowledge about the issues to decide how to vote in the referendum is only four points up on the equivalent proportion in Sir Tom Hunter’s previous poll in January. Nevertheless voters seem as determined as ever to make it to the polls – as many as 75% say they are certain to vote, equalling the previous record high in TNS BMRB’s polls. Voters may not think much of the referendum debate, but they still seem to accept that the issue at stake is one that really matters.

P.S. The TNS BRB poll was conducted over the period of a fortnight in the middle of June. It is thus somewhat older than the most recent YouGov poll. Our most recent poll of polls thus continues to be dated 29 June, while today’s poll makes no difference to the tally of Yes 43%, No 57%.