@gembo for the last Scottish Parliament elections, or the last Scottish European elections?
I assume you mean SP elections as the last Euros were before the 2010 election and the coalition being formed.
There's no easy analysis to the 2011 election. People talk about percentages, but it's numbers of votes that matter. Labour managed to get nearly the same number of votes across the country in 2011 that they did in 2007. But they were overwhelmed by a tsunami for the SNP, whose vote went up by over a third, from 664k votes to 903k.
The LIbs fell from 326k to 158k, with the worst of that falling in the central belt where they were absolutely thrashed. They lost 46 deposits, out of 73 seats.
A collosal loss. But did they vote SNP instead? Polling shows that Lib Dems supporters are almost as unionist as Tories, so personally I don't think so. I think it was a lot murkier than that.
On pretty much no evidence, I think many Libs in central Scotland went to Labour or stayed at home; many Labour voters moved to SNP or stayed at home; many people who hadn't voted in a long time voted SNP, especially in Labour heartland seats (I think because it was the first time people in those seats believed the SNP had a chance of actually winning them - like what happens in by-elections).
Where the Lib collapse really seemed to help the SNP was on the regional lists, just by changing the maths.
It all meant a perfect storm for Labour - the SNP added the most votes in the places they'd always needed them - all those Labour seat where the SNP were clear second, and had been for two decades.
The nuttiest result was in Edinburgh South - this was, in percentage terms, the worst seat on the Scottish mainland for the SNP, and they came 4th in 2007. But the vote fractured and the SNP won it with less than 30% of the vote!
Then, on the regional list, the knife really was turned. The SNP actually did be[i]tter on the lists than in the constituencies, reversing what was an accepted SP norm for them. That, combined with decent numbers voting for parties not making the threshhold, or just limping over it to one seat where they previously had more - LD, Green, SSP, Solidarity, Respect Christians, UKIP, Pensioners - meant the number of votes that mattered was lower. On the lists 85% (H&I) to 90% voted for parties who crossed the threshhold. So where the SNP got 45% of the vote, they were effectively getting over 50%.
Also, on these lists, in many regions Labour didn't outpoll the Tories or LD/ Green by enough, so allowing the SNP to sook up some more seats even where they already had many constituencies.
Last thing to note is that constituencies are worth more than regional seats. There are 73 consituency seats and only 56 regionals. So with the SNP hoovering up constituencies, they built a lead that couldn't be outdone in the regions.
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