Meanwhile we appear likely to end up with AV. Which has some theoretical merits although it assumes voter honesty, which we don't get under FPTP. I dislike the blandness bonus element, it tends to give an assembly of the least-hated rather than the most liked, but it's also faulty.
So for example if my friend and I, Labour supporters, live in a constituency where the results were as follows at this election: Labour 15,000, Lib Dem 9,000, Conservative 8,999, what do we do at the next election?
If everyone votes as previously, it is likely that the Conservative voters will give their second preferences to the Lib Dems, and they will win. If a small cohort of Labour voters switches to the Conservatives, they will come second, and Labour need only scoop up 20% or so of the Lib Dem votes to ensure victory.
In Brighton Pavilion, it would lead to a Labour-Green duel in the final round decided partly by, I presume, the second preferences of Liberal Democrats, but mostly by the 5th versus 6th preferences of Conservatives. If someone wants Conservative, and if not Conservative UKIP, and if not UKIP Lib Dem, and if not Lib Dem an Independent, should their further choice between two candidates they frankly detest really count for as many votes as someone's passionate first choice?