In the interest of balance, following the appearance of Lord Ashdown on Newsnight last night, and of the article we published yesterday about the untruths in the NO2AV campaign, electoral reform expert, Dr Alan Renwick addresses the issues in the 'yes' campaign.

Yesterday I examined the arguments of the No2AV campaign and found that most of those arguments just didn’t stand up to scrutiny. So let’s take a look now at the arguments of the Yes lobby. Do AV’s supporters respect the truth any more than their opponents do?

On the face of it, they do. On their website, they present three key arguments in favour of the Alternative Vote (AV) system, and none of these contain any statements that are outright false. They say that MPs would have to seek the support of at least 50 per cent of voters in order to be sure of election, that AV gives voters more opportunity to express their true preferences, and that “Too many MPs have their ‘safe seats’ for life.”

Scratch the surface, however, and some problems emerge. For a start, some of these statements seem to have been worded very carefully to give a misleading impression without actually saying anything directly untrue. Take that last statement about safe seats. The message that we are clearly supposed to pick up is that AV would end safe seats and thereby destroy the culture of Westminster complacency that generated the scandal over MPs’ expenses. The website doesn’t actually say that – actually, it doesn’t connect AV and safe seats at all – but that is the idea we are supposed to go away with.

Indeed, once we get away from the official line on the campaign website, we find some Yes supporters who choose their words with much less care. Speaking on Newsnight last night, former Lib Dem leader Lord Ashdown was particularly forthright. “If you have AV”, he claimed, “you will not have safe seats”. He continued, “There are no more safe seats, no more jobs for life.”

This, as Lord Prescott quite rightly pointed out, is “absolute nonsense”. In many seats under AV, as under First Past the Post, the leading candidate would sail home on over 50 per cent of the vote. AV in these seats will make no difference. It’s probably true that the number of safe seats under AV would be a bit lower than it is now. But the shift would not be dramatic; nor would it change the culture of politics. In fact, there’s no evidence that the “safety” of MPs’ seats had any great impact on their use of parliamentary allowances. V would not have prevented the abuse of the expenses system. Anyone who suggests otherwise – whether they do so explicitly or by indirect insinuation – is trying to mislead us.

Lord Ashdown also embellished the first of the Yes camp’s arguments, saying that AV “means that every MP in Britain has to enjoy the support of 50% of the poll”. The website claims only that MPs “would have to aim to get more than 50% of the vote”. Here again we find some carefully chosen words designed to amplify reality. It’s true that MPs would need broad support under AV, but it’s not true that they would actually always need 50%. Some voters are likely to express only one or two preferences. So the counting process will sometimes reach the stage where only two candidates are left but neither has more than 50% support, because some voters have not given a preference to either of them. n this case, the candidate with most votes will win. So, yes, AV encourages MPs to broaden their appeal, but, no, it does not guarantee that every MP has majority backing.

Lord Ashdown offered one final argument: AV, he said, “does not deliver more hung parliaments”. He cited Australian evidence in support of this. Now, I criticized the No campaign yesterday for claiming – quite wrongly – that AV guarantees hung parliaments. But in the UK context it would very likely increase their frequency a bit. AV helps centrist parties (because they accumulate lots of second preferences). So it would boost the Lib Dems and make the task of forming a single-party majority a little harder. The difference would not be huge, but it’s enough to render Lord Ashdown’s claim inaccurate.

On this evidence, then, the Yes camp currently score little better than the No camp in their fidelity to the truth. Just like the No side, they’re failing to make much of the strongest arguments in their favour: AV makes it more likely that the most popular candidate in a constituency is the one elected and it largely frees voters of the need to make calculations about tactical voting.

The trouble for the Yes campaign is that neither of these arguments is very saleable: few voters are exercised about tactical voting, and it takes a mini-seminar to explain why the claim that AV is better for identifying the most popular candidate is correct. If voters are to make a well informed decision on 5th May, however, the Yes camp will need to find ways of getting these points across.

For a full and balanced guide to electoral reform in the UK, Dr Alan Renwick's book A Citizen's Guide to Electoral Reform is available now, priced £9.99.