Very interesting and thoughtful post, thank you. I love the idea of a House of Evidence, and of a travelling Parliament.
Rather than pure proportional representation I would tend to favour a hybrid system that preserved some geographic link between voters and representatives.
I think your implied analysis of the FPTP is spot-on. It doesn’t protect us from extremists, even if that were considered a democratically acceptable aim, as indeed it should not be. It disenfranchises a large part of the electorate. Perhaps most dangerously it enforces an effective two-party state.
A two-party state probably worked effectively when the electorate was smaller and more homogeneous and the role of government was less complex, but today we’re polarised along many axes. A two-party system obliges parties to appeal to multiple groups, most of whom will end up feeling cheated. And this in turn makes the two-party system vulnerable to becoming effectively a one-party system, as we’re seeing at the moment with Labour’s left wing ‘hijacking’. Yet, it would be wholly reasonable for Corbyn’s supporters to be represented in Parliament, without leaving the country as a whole minus a representative opposition.
Finally, it’s sometimes argued that the best way to deal with extremists is to involved them in government, with its complexities and compromises and harsh reality checks. Countries across the West are struggling with right wing populism at the moment, but I wonder if it’s coincidence that it’s the US and UK, with their adversarial two-party systems, that are the first to be thrown into chaos. I’m watching France and Germany carefully.