Another busy day for polling. We have only one GB voting intention poll today, but from a brand new pollster (later on we’ll have the regular daily poll from YouGov and the ComRes/Mail/ITV poll). However we also have a new Scottish poll from Ipsos MORI, three new constituency polls from Lord Ashcroft and a new poll of Con-Lab marginals from ComRes.

The new GB voting intention poll is from BMG Research for May 2015. It’s an online poll, using the sort of weightings and adjustments ICM use – so weighted by past vote, weighted by likelihood to vote with people who didn’t vote weighted down, and with 50% of people who say don’t know assumed to vote for the party they did last time. This has produced topline figures of CON 35%, LAB 32%, LDEM 11%, UKIP 14%, GRN 3% – full tabs are here.

MORI’s Scottish poll shows, as ever, a huge SNP lead. Topline figures are CON 17%, LAB 20%, LDEM 5%, SNP 54% (tabs). This would be enough for the SNP to win just about everywhere. A measure of just how vast the change has been in Scotland is that we are no longer surprised by polls showing the SNP with huge landslide leads in Scotland – we should be. A thirty-four point lead for the SNP in an area that Labour has consistently won since the 1960s is astounding and appears to be a true realignment in Scottish politics. We end up paying to the rest of the country because England and Wales are on a knife-edge while the outcome of Scotland appears settled, it’s just a question of how colossal the SNP landslide is, but it’s good to sit back occasionally and gawp at the scale of the turnaround in Scottish politics since a year ago.

Lord Ashcroft released three new constituency polls. The first was of South Swindon – a typical Con-Lab marginal seat, but not of any great importance beyond that. At the last election Robert Buckland had a majority of 7.5%, so with the national polls level we’d expect to find Conservative and Labour pretty much neck-and-neck here. That’s what Ashcroft found in his last two polls of the seat, it’s still the case now – a Conservative lead of just one point.

The other two seats are far more unusual affairs. The first is Sheffield Hallam, Nick Clegg’s own constituency. Ashcroft’s previous polling of the constituency has consistently found a very tight race between Labour and the Liberal Democrats (despite the fact that it used to the Tories who were main alternative to the Liberals here). Ashcroft’s poll today shows a Labour lead of one point, so far too close to call. Interestingly comparing the standard voting intention question and the constituency question a quarter of Conservative voters say they will actually vote Lib Dem in Hallam, suggesting significant Tory tactical voting propping up Nick Clegg.

The last of Ashcroft’s polls was in Thanet South, the seat being contested by Nigel Farage. There has been substantial polling in this seat, with recent Survation polls commissioned by UKIP donor Alan Bown showing a solid lead for Nigel Farage and other polling by ComRes showing a tight three way race between Conservative, Labour and UKIP. Ashcroft found a tight race between Conservative and UKIP, with the Tories just three points ahead, but Labour now clearly back in third place – CON 34%, UKIP 32%, LAB 26%. Tables for all three polls are here.

Finally there was a new ComRes poll of battleground Con-Lab marginals. As I’ve written before, the key to understanding marginal polls is to look at how those seats voted last time, what they change is, and how that compares to the national picture. This poll isn’t the 40 closest Lab-Con marginals that ComRes usually poll in their marginals omnibus, but a different bespoke sample of the fifty most marginal Con held marginals with Labour in second place. In 2010 there was an average Conservative lead of 4 points across these seats, while in today’s poll ComRes found a 3 point Labour lead. This is a 3.5 swing from Conservative to Labour, or the equivalent of a national poll showing Labour and Conservative neck-and-neck. Full tables are here

The 3.5 swing is in line with the national swing across all the polls (though a little bigger than the swing in ComRes’s telephone polls). However, I’m not sure that national polls are the right comparison – almost all Lab-Con marginals are in England, and because Labour have collapsed in Scotland the swing to Labour is actually bigger in England & Wales than the national polls imply. I’m going to try write at more length about the different battlegrounds at the weekend, but at first glance it looks to me as if the Conservatives may be doing a little better in the key marginals than across England and Wales as a whole… but Labour are doing a little better in England and Wales as a whole than in GB, so the two factors cancel each other out and the marginals swing is about the same as the national GB swing.

UPDATE: The voting intention figures for ComRes and YouGov are now both out. ComRes’s telephone poll for the Mail & ITV has topline figures of CON 35%, LAB 35%, LDEM 7%, UKIP 11%, GRN 6%. YouGov for the Sun have topline figures of CON 35%, LAB 34%, LDEM 9%, UKIP 12%, GRN 4%.