For much of last year the referendum campaign had something of the air of a phoney war.

There was, after all, no detailed independence prospectus to debate; the Scottish Government had opted not to publish the White Paper that would detail its plans until the end of November.

The UK Government did its best to stir up doubt and uncertainty with an endless stream of "analysis papers" asking awkward questions about independence, but Mr Salmond largely kept his power dry.

Certainly, the public appeared to be little moved by the initial skirmishes; the average level of Yes and No support in the polls barely moved all year.

The phoney war is, however, now well and truly over.

The eventual publication of the independence White Paper has given the Yes side a cause to promote and the No side something to fire at.

Meanwhile, last month the UK Government decided to change tack somewhat and provide its own answer to one of its awkward questions - the rest of the UK would not be willing to share the pound with an independent Scotland.

The onset of the company reporting season has also seen big business report to its shareholders on the risks or benefits they think independence might bring.

And the polls have finally moved.

There were some signs this was happening in the immediate wake of the White Paper's publication.

Four polls conducted before Christmas all registered small increases in the Yes vote; on average by two points as compared with the equivalent pre-White Paper polls. Even so, at 37% the average Yes vote in these particular polls (after the Don't Knows were excluded) was still hardly enough to quicken the pace of even the most fervent of Yes hearts.

The signs that something really had changed only became clear once the New Year holiday was over. Across all polls conducted since January the proportion intending to vote Yes has been put at 42%, while 58% are reckoned to be inclined to vote No. That represents a three point increase on the equivalent average across all of the polls conducted in the second half of last year.

Just one polling company has failed to register any post-White Paper increase in support. Ironically, that company is Panelbase, whose polls last year were markedly more optimistic for the Yes side than those of any other company, putting them consistently as high as 44- 45%. The two polls the company has conducted so far this year have put the Yes tally at 43-44%. However, this does at least mean that Panelbase's polls no longer stand out as exceptional, thereby lending rather greater credence to its figures.

That said, the pollsters are still far from all being in agreement with each other. During the past two and a half months the Yes vote has been put as low as 36% and as high as 46% - the difference between the prospect of a very comfortable win for the No side and that of a real race between now and September.

Little wonder, then, that both campaigns have, through selective quotation, been able to tell us that the polls are leaning that way.

The intelligent observer will simply remain aware that there is still considerable uncertainty about exactly how close the race is.

Moreover, even if we accept the current poll average as accurate and that thus there has been some narrowing of the referendum race, the change is better described as modest rather than dramatic. Every single poll continues to put the No side ahead. Still eight points short of the winning post, if they are to win the Yes side will have to make almost three times as much progress in the next six months as the three point increase it has achieved in the past three.

But why have the Yes side made at least modest progress? In truth, very few polls are consistently asking people's views about some of the underlying key issues in the campaign, thereby enabling us to gain some idea as to why people might have changed their minds.

One exception, however, are polls by ICM that have repeatedly asked people both whether they think independence would be good or bad for Scotland's economy, and whether it would result in more or less inequality. These are, of course, two of the central themes in the Yes campaign.

Of the two issues, it is clearly the economy that matters more. No less than 97% of those who think that independence would be good for Scotland's economy say they intend to vote Yes to the proposition.

In contrast, only 63% of those who think there would be less inequality are minded to vote in favour of leaving the UK.

And the proportion who think that independence would be good for Scotland's economy has edged up from 31% in September to 35% now - though it is also clear that many Scots still remain to be convinced of the economic case.

Doubtless, the apparent importance of the economy in voters' minds helped persuade the No side to announce an independent Scotland would not be allowed to share the pound.

Surely such an announcement would help make the economic risks of independence clear to voters?

It has not worked out that way, however. At 42%, the average Yes tally in the six polls conducted since the currency announcement is actually one point higher than its tally in the polls conducted immediately beforehand.

Rather than pushing voters into the No camp, the announcement has simply polarised opinion.

While most No voters agreed that it was not in the interests of the rest of the UK to share the pound, most Yes voters (some of whom do not wish to keep the pound anyway) accepted Alex Salmond's argument that Mr Osborne was bluffing,

Meanwhile, undecided voters divided more or less evenly down the middle. 'Project Fear' evidently has its limitations.