In a two-party first-past-the-post electoral system (FPTP), capturing a party is the only way to change politics: FPTP’s iron electoral law bars new parties emerging to react to new circumstances. The worn-out defence of FPTP is that it creates “stability”: that’s not how the US feels, lurching from Barack Obama to Trump to Biden, the system denying coalitions of compromise. Both countries’ democracies are failed by their archaic voting systems.
Such a theory has to be able to explain the rise of the SNP in Scottish politics. Which is it doesn’t.
But then Polly was SDP and she needs an explanation for why that didn’t work. And the idea that it was just pants isn’t to her taste.