Scottish marginals & the seats to watch - a thread. /1

At every general election, the real battle is only in a sub-set of seats, the marginals. /2

Scotland has a lot of marginals. Across the whole of Britain, there are 169 seats (out of 650) where a swing of less than 10% is required. In Scotland, well over half of seats are marginals, 46 of 59. /3

(And some are really marginal. In North East Fife, the SNPs majority is just 2!) /4

Lots of these (30 of the 46) are held by the SNP. If there was a swing away from the SNP, these would be the main battleground. /5

But, given recent polling has pointed to a rise in the SNP vote, all are very likely to be easily held (bar a couple of notable exceptions*). So, generally, the most interesting marginals will be the non-SNP seats. Let’s look at them. /6

Labour hold 7 seats. Of these, 6 are marginal. Indeed, their 2nd safest seat, East Lothian requires only a swing of 5.5% to the SNP. If SNP achieve this, Ian Murray in Edinburgh South will probably be the only Labour MP left in Scotland. /7

For the Lib Dems, one of their four Scottish seats is marginal. Edinburgh West. It would take a swing of 5.7% to the SNP to unseat them here. This could be a close race and one to watch. /8

However, the real interest will be in the Tory seats. They hold 13. In all of these, the SNP came second in 2017. Should the Tories manage to limit the swing to SNP to less than 4.9%, they are in danger in only one - Stirling. /9

Anything more, and small differences in swing could make a big difference in seats. A swing of between 4.9% and 6.6%, and up to a further 4 seats switch to the SNP. For a swing of between 8.7% and 10.9%, up to 5 more would go. /10

Therefore, there is a very small difference in terms of share of vote between the Tories holding 12 of their 13 seats in Scotland, or just 3 of the 13. /11

*Of course, if Tory upsurge in Scotland outstrips that of SNP, there are 5 seats were a small swing (<3%) would see Tories gain from SNP: Perth & N Perthshire, Lanark and Hamilton E, Edinburgh SW , Argyll and Bute, and Central Ayrshire. /12

*For LibDems, only in North West Fife does it look like they have a chance of a gain. /13

So, seven seats to watch…..... /14

SNP v Labour - East Lothian (swing needed 5.5%): If SNP gain this, Labour are likely to lose all bar Ian Murray’s Edinburgh South to the SNP. /15

SNP v Con - Perth and North Perthshire (swing needed 0.04%): The Conservative’s Number 1 target in Scotland. Win here, and they should be increasing their representation in Scotland. /16

SNP v Tory - Ayr, Carrick and Cumnock (swing needed, 6%): Gain this, and it’s likely that the SNP will gain at least 3 seats from Tories. /17

SNP v Tory - Moray (swing needed 8.7%): Gain this, and it’s likely that the SNP will gain at least 6 seats from the Tories. /18

SNP v Tory – Dumfries and Galloway (swing needed 10.9%) Gain this, and the SNP will most likely have won 10 of the 13 Tory /19

SNP v LD: North East Fife. (swing needed 0.005%!) The one seat in the UK were no one can quibble that the LibDem bar chart is overstating just how marginal it is. /20

& SNP v LD: Edinburgh West. (swing needed 5.7!) If SNP win here, it’s likely they will main gains for all three other major parties and be close to repeating their performance in 2015. /21

Final caveat. All based on Uniform National Swing. UNS has been pretty good historically, but there may be local differences that buck the trend. For methodologists, one fascinating area is how much, if at all, MRP outperforms UNS at this election. 22/22