For those wanting to gauge the state of the Scottish independence race, today's polls present a particularly murky picture. A new Survation survey in today's Daily Record puts the Yes side 12 points behind (56-44, excluding don't knows), but a Panelbase poll has them trailing by just six (53-47). Even less helpfully, the discrepancy cannot be explained by methodological differences since both companies use weightings based on the 2011 Scottish election, rather than the 2010 general election.

But despite the gulf in the figures, there are three common trends worth noting. The first is that the race has indisputably narrowed (whatever your pollster of choice). Back in November, the Yes vote stood at an average of 38 per cent, compared to 62 per cent for No. But so far this month, Yes is on 46 per cent with No on 54 per cent. The Unionists' lead has fallen by two-thirds from 24 points to just eight. This is despite the No campaign using what many regarded as its most potent weapon - the pledge to veto a currency union - and José Manuel Barroso's warning that it would be "extremely difficult, if not impossible" for an independent Scotland to join the EU.

The second is that, for now at least, the Yes side's advance has stalled. The six-point gap shown by Panelbase is identical to that shown four weeks ago and the 12-point gap shown by Survation is a point higher than that in last month's poll. It's too early to say for sure, but the Yes vote may well have hit a ceiling.

Finally, it's worth making the obvious but significant point that every poll continues to show the No side clearly ahead (as has been the case since the campaign started). While it's not impossible that this will change before 18 September, it is unlikely. A narrow defeat might allow the SNP to press for devo max (and even to revisit the independence question at some point) but a defeat it will be.