I think this is the key point. Proportional representation is very simple to understand, and likewise first-past-the-post (in its essence, at least; the actual implementation we have in the UK perhaps less so). Alternative vote is plainly more complex - first something happens, then perhaps something else happens, then... etc; it's not complex for smart HN readers, but even trying to explain it in a few words shows it's more involved than the other two systems.

I am fundamentally uncertain that a majority of the electorate understood AV when they were voting - and this was certainly supported by my own conversations at the time with moderately intelligent people who plainly did not understand it. And, in fact, the majority of the electorate did not even vote at all on the issue.

Proportional representation is undeniably more democratic than either FPTP or AV, but it does mean you end up having to live with the fact that a rather alarmingly large proportion of people have views that the majority find unsavoury (eg. the BNP managed nearly 2% of the votes in the 2010 election).

>it does mean you end up having to live with the fact that a rather alarmingly large proportion of people have views that the majority find unsavoury

That's democracy for you.

Besides, the BNP arose from a climate of austerity and declining real incomes. If you have a functioning political system that doesn't do that to the majority, you deprive the unsavory minority of political oxygen.

They ran the message "it's too complicated for you to understand", and most accepted that at face and spent no more thought on the matter.

Same phenomenon as "math/computer is hard" being acceptable and an excuse not to try, or even listen. You can see the roller shutter come down in their eyes.