I am not in favour of STV. However, a proportional system would prevent anyone from governing alone without 50% of the vote. I think that would apply to both Labour and Conservative, who would be likely to split. Thus government would be more likely to consist of more than one party.
Mike, you keep saying this but in practice it isn't true.
Spain 2011: People's Party 186 seats out of 350 on 44.6% of the vote Scotland 2011: SNP 69/129 on 45.4% constituency vote and 44.0% regional vote Turkey 2015: AKP 317/550 on 49.5% of the vote
This list could be extended substantially.
In the real world, so-called proportional systems do not guarantee the feature you suggest.
Depends on the details of the system but in any case all are considerably better than FPTP, notably in 2005 and 2019 where results greatly enhanced the seat total of the leading party. Not to mention the virtual impossibility of proper representation for smaller parties. Perhaps you could list all of the examples which do not coincide with your outliers and display coalitions of parties who did not win 50% of the vote. You'll be a while!!
sensible parties would also provide a range of different candidates within the same constituency .
again, that does not happen, except in the vivid imagination of proponents of STV
It would happen as an inevitable feature of the system (not a bug), *if* the parties selected their candidates by STV in the first place. Where the theory falls down is that the publicity for the parties would emphasise the unity of the candidates rather than their differences.
As stated elsewhere, the cleavage in the voters’ minds would focus more on locality ( candidate A coming from village X) or incumbency/ novice, rather than ideological differences.
It may be worth reminding that I stopped being a “proponent of STV” when I left the ERS in 2015.
Labour governments are always voted in by empty minds, and voted out by empty pockets