There’s been a fair bit of speculation today following the latest YouGov/Times poll that all might not be lost for Tories in tomorrow’s by-election. Maybe but according to standard swing calculations BJohnson’s party needs more movement than this to fend off the yellow peril.
Swing is calculated by looking at the poll shares in relation to what happened at the general election. So the Tory GB share on June 8th 2017 was 43.5% which is 11.5% greater than today’s poll. The LDs, on the other hand see an increase in their GB share from 7.6% at the general election to 19% in the poll so a movement up of 11.4%. Taken together the poll represents a CON to LD swing since GE2017 of 11.45%.
Based on the Brecon 2017 result the LDs need a swing from the Tories of 9.75% to win.
This is all theoretical stuff, of course, but expect at some stage on Friday projections of many current CON held seats would be at risk if the swing at B & R was repeated.
Of course there is a long history of by-election swings not being replicated at general elections and of many LD gains going back to the Tories at the following general election. One big difference now is the weakness in electoral terms of JCorbyn-led Labour.
The general point is that whilst the BJohnson-led party might be eating into the Brexit party vote there may even be bigger dangers from a resurgent grouping of anti-Brexit parties who are showing in this seat how they can be a lot more effective working together.
It is that which could have the biggest long-term impact. First past the post might no longer be the Tories’ great saviour.