This TNS poll is so God-awful for Scottish Labour that J K Rowling didn't even have a perfect response to effortlessly shut it down

The monthly TNS poll of Holyrood voting intentions came out earlier today, and the big news is that Labour have returned to their all-time low of 19% on the constituency vote.  They've only previously had one sub-20 showing on the constituency vote with TNS, and that was during the initial honeymoon period after the SNP's landslide victory in the UK general election last year.  To put it in perspective, they had recovered to as 'high' as 24% during the autumn, so it appears that something has gone seriously wrong since then.

Constituency ballot :

SNP 56% (-4)
Labour 19% (-2)
Conservatives 15% (+2)
Liberal Democrats 6% (+2)

Regional list ballot :

SNP 47% (-8)
Labour 21% (n/c)
Conservatives 15% (+2)
Greens 8% (+2)
Liberal Democrats 6% (+2)
SSP 2% (+2)
UKIP 1% (+1)

Is there any cause for concern in the apparent drop in support for the SNP?  Not necessarily on the constituency ballot, because 56% remains within the normal TNS range for the SNP, albeit at the lower end of it.  However, 47% on the list ballot is easily the lowest TNS have reported since before the general election, and perhaps more importantly, the disparity between the two ballots is much bigger than normal.  Unlike with Survation (who routinely show the SNP losing a big chunk of their constituency voters on the list), that can't be explained by an inadvisable question wording.  The explanation offered by TNS themselves is that, as the election approaches, more voters may be recalling that they do have an option of using the list vote for a different party.  I'm slightly sceptical about that, because almost half of SNP constituency voters who switch parties on the list in this poll end up in the column of an anti-independence party.  If it was simply a case of SNP voters being emboldened to be more adventurous on the list, you wouldn't expect them to be going to Labour.  I'm wondering if we're just looking at a slightly weird sample here, but future polls will tell us one way or the other.

All the same, this is a moderately good poll for two of the smaller pro-independence parties.  8% for the Greens isn't unusually high, but it's towards the upper end of their normal range with TNS.  2% for the SSP is still well below the level at which RISE can realistically expect to win even one seat, but it does mark the first time since heaven-only-knows-when that any firm other than YouGov have put the SSP or RISE higher than 1%.  Time will tell whether that's a freak result.  The news remains grim for Tommy Sheridan's Solidarity, though - they're listed in the datasets, but they failed to trouble the scorer.  In the weighted sample, not a single respondent was a Solidarity voter (although the presence of an asterisk implies that they probably had a solitary voter in the unweighted sample).

Incidentally, UKIP would have joined the SSP on 2%, but they lost two-thirds of their voters when the turnout filter was applied.  That might be a little clue as to why David Coburn and his delightful chums are highly unlikely to grace Holyrood with their presence after May.  The European election two years ago was effectively a 'home' game for them, with their supporters disproportionately motivated to turn out, but a Scottish Parliament election is very much an 'away' fixture for the Brit Nat ultras.

*  *  *

SCOT GOES POP POLL OF POLLS

I never got round to updating the Poll of Polls after the most recent Survation poll, so the percentage changes below take account of both Survation and TNS.  This is the first update in which Labour have slipped below 20% on the constituency ballot, although of course we're well used to seeing them below 20% on the list.

Constituency ballot :

SNP 52.4% (-0.8)
Labour 19.8% (-0.6)
Conservatives 16.6% (+0.4)
Liberal Democrats 6.2% (+0.8)

Regional list ballot :

SNP 45.8% (-1.8)
Labour 18.8% (-0.2)
Conservatives 16.8% (+1.2)
Greens 7.4% (+0.6)
Liberal Democrats 6.4% (+0.2)

(The Poll of Polls is based on a rolling average of the most recent poll from each of the firms that have reported Scottish Parliament voting intention numbers over the previous three months, and that adhere to British Polling Council rules. At present, there are five - Panelbase, Survation, YouGov, TNS and Ipsos-Mori. Whenever a new poll is published, it replaces the last poll from the same company in the sample.)