Enthralling YouGov poll sees SNP maintain massive 24% lead

The frequency of Scottish polling seems to be increasing markedly as we approach election day - YouGov have tonight released a new full-scale Scottish poll, just ten days or so after their last one.

Scottish voting intentions for the May 2015 UK general election (YouGov, 16th-20th April) :

SNP 49% (n/c)
Labour 25% (n/c)
Conservatives 17% (-1)
Liberal Democrats 5% (+1)

This may look like a routine no change result, but in fact it's hugely significant.  The last YouGov poll saw both the SNP vote and the SNP lead over Labour soar to record-breaking levels.  The general rule of thumb is that no sudden change is meaningful until it's confirmed by a second poll showing much the same thing - in a sense we've already had that confirmation from TNS and Ashcroft, but it's still important to get a repeat poll from YouGov itself.  There can now be absolutely no remaining room for doubt that the SNP lead has increased still further over recent weeks, although pinpointing exactly when the additional surge occurred is quite difficult.

I'll have to wait until the datasets appear before I can say much more of any use, but the other obvious thing that leaps out straight away is that the bulk of the fieldwork for this poll appears to have taken place after the BBC leaders' debate on Thursday night.  So there doesn't seem to be any comfort for Polly Toynbee and her startling theory that Ed Miliband's performance in that debate would help turn things around a little for Scottish Labour.  Admittedly, we've been told that the poll does show a significant improvement in Miliband's personal rating, but he's still light-years behind Nicola Sturgeon, and for as long as that remains the case there's no rational reason to suppose that the leadership factor will help fuel a late Labour comeback.