What about if I go to now some of the more technical things about AV. Alan Renwick – his view is that AV is an improvement on FPTP, but actually by far not the ideal system. One of his arguments against AV is in certain landslide elections AV can actually veer almost on being unconstitutional to the extent that it actually exaggerates landslides. He points to the election result of 1997, and questions the legitimacy of the result based on AV. What do you make of that kind of argument?

The BBC did an analysis with some academic. And it first of all showed that generally having AV since I was born, since the 1980s, wouldn’t have actually changed the outcome of any election in terms of which party won. And it would only have produced a balanced Parliament in 2010 which of course we got with FPTP anyway. So it’s not likely to change hugely the nature of what kind of governments we get, but it is true that that analysis showed that in the landslide election of 1997 and I think possibly in 1983, when the Tories did very well, that Labour would have done even better in 1997 and possibly I think if my memory serves me correctly the Tories would have done even better in 1983. But there was a real ground swell of opinion in 1997 that people wanted to get rid of the Conservatives so I think in a sense that would still be in-keeping with the sentiment of the country at that point. At the end of the day, it’s how people vote. Basically that becomes that a particular party becomes very unpopular. But if a particular party is very unpopular then perhaps they shouldn’t have as many MPs.

The counter to that is having a government that is almost too strong, that you have something that is almost too powerful. You need a check on the other side of that.

It’s a valid point but it’s a point under FPTP. Because the public voted in that way, Tony Blair did have a massive majority and he had that under FPTP. So you might be talking about issues that have decreased slightly but he had a majority of 160. If he had a majority of 180, I don’t think that would have made a massive difference. By having this two-party system, that is one of the problems with it, and that’s one of the arguments for perhaps even a more radical change maybe. But that’s not what we’re discussing at the moment. What you do have in that scenario, is you do need to have a strong opposition and the Liberal Democrats managed to provide a lot of that in the first terms of the Labour government on 1997 and 2001 and also you’ll find that the media starts to play that role, pressure groups and organisations in the country. There are other parts of a civil society that can provide that scrutiny of the government, and that does happen. Ideally you’d have – I think it’s quite healthy when parties don’t have large majorities, where parties might have to work together with other parties in order to get things agreed. Actually I think that’s a good thing. But we ultimately need to listen to what the voters are saying, and sometimes the voters will be very, very clear.

Renwick's other argument is that AV encourages centralist candidates, because you might need to appeal to both the Left and the Right to win a seat. Sometimes you get more compromise candidates then you would under FPTP.

First of all, I would point out that argument entirely demolishes the argument that AV encourages extremists, that we were discussing a second ago. But at the end of the day if people get enough first preferences, if they get 50% of the vote in the first round, then the fact that it is AV is irrelevant to the whole FPTP thing. We’ve currently got that system where you need to get more votes than anybody else – what you currently get is you can have just a few more votes than other people but be by far not the generally preferred candidate. Famously people have won on 26% of the vote. Even if you are a Conservative MP, you are still representing Conservative constituents who voted Labour, and you need to be somebody who can still be approachable to them and can listen to them and understand them. You might have very different political views but you need to be able to reach across a political divide even if it’s not always in agreement. And so I don’t think it would necessarily encourage candidates with centrist views. I think it would encourage candidates to make sure that they reach out across a political spectrum to recognise that not everybody’s got the exact same viewpoint as them. And where you do differ, you have to explain that. But I do think that point also means it does discourage very extreme candidates and I don’t think that’s necessarily a bad thing.

Well it may discourage them from being able to win.

Yes, I would never want to discourage them from standing for election, but it reduces the likelihood of very extreme candidates winning, and that’s a good thing.

What about the differences between working on a general election compared to a national referendum?

Well obviously the big difference is that it’s not party political. When I’m fighting a general election campaign, it’s my local team, my Liberal Democrats. This is working with people from other political parties. I’ve been into the Yes headquarters in Glasgow. But I also know that Willie Bain and Anas Sarwar have been helping out, Labour MPs. Also, there are lots of people who never normally get that involved in a general election campaign, except for being quite interested, because they feel quite shut out because of the party politics. They don’t associate themselves with a political party. But there are loads of people that you meet who are really quite passionate about electoral reform and the need to fix our politics and they’ve had this opportunity to get involved. Very often when you go in, you might be campaigning alongside somebody who is from a different political party and somebody who’s never done active politics because they’re not of a particular political persuasion. That’s the big difference, and that’s quite refreshing.

A lot of the coverage has been quite Westminster based with, for example, Ed Miliband saying he wouldn’t stand on the platform with Nick Clegg. Do you think that was a mistake?

I think it was probably quite unfortunate. I think when you say the coverage has been quite Westminster-based, I’d say that’s probably because many of the journalists are Westminster-based and maybe don’t get out of the bubble enough. Because I think the campaign isn’t Westminster-based, as I say the campaign is active in different parts of the country. Many of the launches have been in different parts of the country. Sometimes there’s a problem that the Westminster media like to focus on more personal issues.

Would you, or have you stood on the platform with Ed Miliband?

I don’t think I have. Yes of course I would. I’d stand on a platform with anyone who shares my views on this. Where you agree with somebody you should work with them to make change happen.

No system is perfect as we have discussed, but what’s the most imperfect thing about AV?

It’s not STV. I suppose it’s not a proportional system. It’s a preferential system which is a great step in the right direction, but it’s still not proportional. It will give a better result, a better reflection of what people voted for, but it’s not perfect and even STV’s not perfect. Because although I am a big fan of STV, you do still have a constituency link, you do lose the one MP per constituency which a lot of people like as well. You can look at those two systems and you can say well that’s an advantage of one and that’s an advantage of another. As you say no system’s perfect.

How have you found the No to AV campaign's approach compared to you campaign's approach?

I’ve found it strange. I did the Newsnight debate on it and I felt their posters were just quite distasteful. Their suggestion that if we change the voting system, babies will die. I just thought, it’s not true and it’s really a bit irresponsible to try and run that kind of advert. But the main thing I’ve been surprised about with No to AV is that they don’t make the case for FPTP. What they haven’t done is make the case for the system they want to keep. That is very telling. Because I think you can’t make the case for the FPTP system, certainly not over AV, because they are similar, you still have single member constituencies. It’s just better because the voter gets more say under AV, and that’s why they can’t make that case. In a sense it still surprises me that they make it all about personality or scaremongering. Whereas I think the Yes campaign has been making the case for change, pointing out what’s wrong with the current system but what the advantages of AV are.'You

Tags: Alternative vote (AV), Alternative Vote referendum, BNP, Electoral Commission, Electoral Reform Society, Extremism, Full transcript, Jo Swinson, Nick Griffin, Voting machines