Pay particular attention to the Alternate vote example, and see just how unproportional Labour's preferred version is, and how much worse it is than FPTP.
Isn't Labour's preferred system AV+ not AV? Also, the BBC have to have made an assumption to create those figures since we don't have second choice vote preference records. Finally, the feature of AV that distinguishes it from other systems is that it models not just voter preference but also vote revulsion. Since the Tories are the party least of the populus want as the government and most really don't want as government (according to YouGov) AV would tend to reduce their seats.
I'm not a big fan of straight AV to be honest, negative preference has a certain air of "tyranny of the majority" about it, and it would do nothing to solve the larger problem of the two party system since it too tends to favour voting as a herd over principled voting. AV+ would be a bit better, but it still strikes me as a curious half way house which doesn't much advance matters and I'm not a fan of mixed member systems.


