The BBC don't know their AV from their SV; and therein lies the problem...

One of the biggest arguements against any form of PR - aside from it being used as a fig leaf from a decaying government of course - is that it is complicated for the public to understand and PR system lead to higher numbers of accidently spoilt ballot papers.

So the BBC goes to prove the point when today it said on its website:

ALTERNATIVE VOTE
Voters choose their first and second preference and a candidate can only be elected in the first round if they get 50% of the vote
If no-one achieves this in the first round, all but the top two candidates are eliminated and their second preferences redistributed
The candidate with the most votes is then elected

As any AS Politics student can tell you, that isn't true. AV involves the elimination of the bottom place candidate and the votes get redistributed in rounds. The system being described by the BBC is SV, that which is used for the election of the Mayor of London.

Why does this matter? Because LibDems hate SV because it usually traps them out of contention. Let's say the result was:
Con 36, Lab 30, LibDem 28, Green 6
Under SV both the LibDem and the Green would be eliminated and the Labour candidate would probably win.
Under AV, the Green is eliminated which may put the LibDem above Labour; Labour is then eliminated and the LibDem might just win.

But if the BBC cannot get this right, what chance the political class or the public?

This proves the point perfectly.