@powerab mainly but of course anyone can chime in...
Any chance of a major push for electoral reform being retrofitted on consideration in the "Cardiff Accords?"
In Europe in general, the majority of nations have some kind of party-based semi-proportional electoral systems. I call them "semi" because rather few go on a straight basis of total national proportionality, most breaking the nation up into regions in which proportionality prevails more or less, but this can lead to national disproportionality of course.
Now "proportional" in this sense necessarily refers to the electoral system recognizing parties and thus to some degree privileging party organizers, something that opponents of reform in nations that don't have these systems or are discontented with blame for problems. And certainly I do think one can provide for the benefits of party-proportionality in ways that privilege party organizers and big wigs a lot less--but guess which alternatives faced with these choices the party big wigs like to promote and which they like to discredit?
Meanwhile--across the Irish Sea, back in the settlement leading to the Irish Free state and eventually fully independent Republic, it was the British negotiators who demanded that Ireland's legislature (the democratically elected lower house, the upper Senead is appointive) the Dàil, should be elected by Single Transferable Vote, with districts ranging from 2 to 5 members. They did this because they anticipated the interests the Unionists backed as being overwhelmed and shut out of all power if Ireland adopted the same first past the post single member district system that Britain has relied on for centuries. Now I hardly think STV is the perfect electoral system, I think giving voters express ability to get party-proportionality is pretty important and not just for established parties either, and have some radical though to my mind simple and straightforward solutions. But in the context--conservative Junta supporters versus a rising oppositional majority that leans farther left than right, and harks to continental models perhaps, and with British tradition largely discredited through having broken down in the Junta--might not STV emerge as a compromise solution? Unlike systems that formally grant key electoral roles to parties, STV is in principle party-agnostic, like FPTP what is happening in theory is a contest between individual candidates for office from a particular district, in isolation from all others in the nation. There is no need to notice the existence of parties at all, as far as determining which candidates win seats go; in theory ballots and outcome reporting can fail to mention any party affiliations whatsoever. Yet, to a limited and distorted degree, the mechanism can in fact be said to be semi-proportional. Sort of--the fewer the average number of members in a district, the larger a group can be and still fail of representation, and I have graphed the outcomes of the Irish Dàil elections from the early '80s to the present day plotting share of representation in the Dàil won versus share of (first choice) national popular vote and can show the systematic pattern of distortion in favor of the larger parties, squeezing out of smaller ones and randomization of shares of intermediate ones.
However in the circumstances, might it not emerge either directly from the Cardiff Accords, or as a broadly popular party platform shared by the left wing and separatist parties if rejected by the Nationals, to implement STV in Britain?
A specific scheme I would suggest might be adopted would be to form the existing 600 odd constituencies consistently into 200-odd 3 member groups, for a uniform national system of consolidated three member districts. Three is a low average for purposes of gaining proportionality IMHO, five might be a lot better--but such districts would not be tremendously large, the computational mechanics of the STV process would be simpler than in larger districts, and there is much to be said for uniformity.
OTOH, the UK House of Commons has a rather poor history of achieving uniformity in district sizes OTL, and it might be that three might be adopted as a minimum (avoiding or forbidding 2 member districts) but local constituency voters might be given the option of forming larger districts with mutual majority approval--four neighboring standard districts might vote to reform into 3 four member districts or 2 six member; five might reform into three 5 member districts, and so on--I don't think there will be much support for individual districts being larger than 7 member. If there is a diversity in numbers of district members but fair proportionality in population to member, then the more limited opportunity for smaller parties presented by the standard 3 member district might be offset by the larger districts opening more doors.
One reason I could see STV being promoted is that all groups have some reason to fear being shut out out of proportion to their numbers.
Another is that adoption of STV has a track record mainly in English speaking nations. Australia uses it for their Senate, and I believe the system was invented in the USA as a once quite widespread reform of city government. Now in the USA it was largely purged away in the pretext that it was misrepresented as a "Communist" scheme, but in the context of a Junta government grudgingly but with a sense of necessity seeking to negotiate a transition back to democratic validation of HMG, such Blimpish talk would have little traction with the dissident majority that has heard plenty of such cant over the decades, whereas the conservatives themselves might fear being shut out of power if simple pluralities carry the boroughs and ridings. (The distinction between "borough" and "riding" might ironically have to go by the board in the process of consolidating traditional constituencies into triple groupings of them; it would often be the case that a borough is fused with its country counterpart into one sensible regional district incorporating both urban and suburban/rural voters).
As I alluded, I personally don't think STV would be entirely satisfactory from the point of view of maximizing and equalizing the power of each voter. It would be likely to favor the persistence of a "two and a half party system" but that of course should be appealing to British sensibilities, as it has been the House of Commons pattern for hundreds of years.
I'd want to improve on it, but there are reasons the sort of improvements I would recommend might work well on the basis of STV ranked choice voting. Meanwhile just adopting it as is full stop would be a compromise between Continental-influenced party proportionalists and die-hard defenders of the virtues of FPTP.