Following an assertion on social media, I chose to look at two recent parliamentary by-elections for their consistency with national opinion polling.
The two latest by-elections in Peterborough and Brecon & Radnorshire both show consistency with timely opinion polls.
In Peterborough and Brecon
The Peterborough by-election was forced by the first successful recall of an MP under the Act of 2015. Fiona Onasanya was formerly a Labour MP — who had the whip removed prior to the successful recall — after being found…