I think these people are missing the big picture here.

Nick Clegg: I could work with Labour, just not with Gordon Brown.

What Nick Clegg actually said:

I just don't think the Britishpeople would accept that he could carry on as prime minister, which is what the convention of old politics dictates when, or rather if, he were to lose the election in such spectacular style

and the Guardian respond:

Clegg's new formula raises the problem of how Labour could replace Brown, as well as the prospect of Labour having a second prime minister who has not won a mandate at a general election.

But I think that's wrong, Labour don't need to replace Brown. Clegg didn't say that he couldn't work with Brown, only that Brown can't be PM. But what if a Brown led Labour Party offered to support a Clegg Prime Ministership? Brown could be in Clegg's government, just not as PM. Labour would then have some time to elect a new leader.

Cameron accused Clegg of:

Cameron accused Clegg of wanting PR "so we have a permanent hung parliament, a permanent coalition, so we never have strong and authoritative and decisive government".

Which is a bit of a weird argument. He doesn't explain why it is in Clegg's interests not to have "strong decisive government", or why it is in the UKs interests to have a "strong decisive government". In my experience "strong decisive governments" often make the wrong decisions, and the rest of us are stuck with them. I'm for weak consensual multi party government that actually has a mandate myself.

Cameron then says:

It's now becoming clear he [Clegg] wants to hold the whole country to ransom, just to get what would benefit the Liberal-Democrats.

Which is possibly the most hypocritical thing I have read during the election campaign. I mean why does Cameron support FPTP? It couldn't be because it benefits the Tory Party? i.e. a majority in parliament on a minority of votes. It's frankly odious when politicians try to take a high moral stance like this and don't even appear to notice the massive hypocrisy in what they say. Labour and the Tories like FPTP because it has allowed them to stich up politics, and ignore the wishes of the majority of voters for the last 65 years at least. To claim that the Lib-Dems support PR because it suits them is a statement of the bleeding obvious, but PR doesn's discriminate in favour of the Lib-Dems, it only gives their voters an equal voice to Labour and Tory voters. Clearly Cameron thinks those voters don't deserve an equal voice. Then he has the effrontery to ask progressives to vote for him? I could never vote for a party that is so elitist, and treats voters with such great contempt that they seem to think we don't understand when we are being patronized.

UK journalists really are ignorant about ho coalitions work.

Jackie Ashley in the Guardian today displays a real lack of understanding about how coalition politics can work. Some of what she says is just plain ignorant. Here's my response, another small 'c' conservative Guardian journalist displaying their utter incomprehension about how coalition politics works. Jackie Ashley, like many at the Guardian, just doesn't seem to be able to get her head around the idea that coalition politics is about compromise.

So imagine if all those left-leaning voters produced a Cameron-led government?

So what if they did? We're not talking about a Tory government, we're talking about a coalition. Many on the left are fed up with Labour because of social and liberty issues, if a Lib-Con coalition can scrap ID cards, and give us our freedom back, many on the left would be happy with that, even if they don't like the coalition's economic policies.

What would the Lib Dem grassroots make of it all?

What indeed? The Lib-Dem grass roots are in fact the most enthusiastic about PR, and PR would mean always having coalition governments. In fact PR would mean that the Lib-Dems would sometimes be in government with Labour, sometimes with the Tories and sometimes in opposition. Lib-Dems understand that because they support PR. Is that a difficult concept to understand?

First, he has let it be known he has an open mind about some kind of electoral reform. I think it's a honey-trap and that the Conservatives would block change.

You don't seem to understand how politics would work in a coalition. The Lib-Dems have already forced the Conservatives to move on PR by showing that they may well hold the balance of power. Coalition politics will always be a negotiation between parties, if there is a Lib-Con coalition then the parties will be partners, not adversaries. If a deal were made then a reform of the electoral system would be government policy. It was claimed in Wales that a referendum on increasing the powers of the NAfW was a "honey trap" by Labour to get Plaid support. But guess what, now we're going to have that referendum. The Lib-Dems must make sure that any coalition has a properly negotiated agreement before entering, like Plaid did with it's One Wales agreement. But reform of the electoral system will itself be a negotiation, the Lib-Dems want STV, but we might get something else because the Tories might have their own ideas. Whatever we get it must be much more proportional that what we now have. I think AV+ is out of the question as not proportional enough for the Lib-Dems, but the Tories might favour MMP or some such system.

The more I look at the prospect of a Con-Lib coalition, the more I think it is not sustainable for long.

It depends how much good faith there is, right? If one party or the other is negotiating in bad faith, and is not prepared to compromise, then it can't work. The Tories will have to understand that a coalition with the Lib-Dems is not synonymous with Lib-Dem support for an entirely Tory programme. Most politicians know this though, most have worked with politicians from other parties in the past, it's only for show that they take these diametrically opposed stances because the electoral system demands that politicians pretend that they hold no views in common whatsoever. If anything the debates have helped demolish that by showing Cameron agreeing with Both Brown and Clegg. But even if a Tory/Lib-Dem coalition fails, then the question is, do we have another election, or does the Labour party try to form a government with the Lib-Dems? If the Lib-Dems hold the balance of power, and a Tory/Lib-Dem coalition fails, there is no call for a new election, the Labour Party would be within it's rights to try to form a government with the Lib-Dems. Of course it'd be up to the Queen in the end, if Cameron dissolved the coalition and demanded the dissolution of parliament, the Queen could say no (especially very early on in the parliament), and ask the new leader of the Labour Party to try and form a government. This happened in Ireland, right? With their Rainbow Coalition.

Proportional Representation.

Electoral systems that are specifically designed to produce a result in which a party's proportion of seats closely reflects the proportion of votes it receives in the election are collectively known as proportional representation systems. Whereas the single transferable vote is technically not a proportional system, but a preferential system (as is the alternative vote), because it was not specifically designed to produce party proportionality, the results it produces are broadly proportional and in some special circumstances it will produce identical results to party list proportional representation.

List PR.

List PR is the simplest form of proportional representation, it is used in many European countries, and is used in the UK to elect members of the European Parliament. Electoral districts (constituencies) are multi-member, and each party will elect the same proportion of members as the proportion of votes it receives. There are many ways to determine how candidates are elected, Finland and the UK use the d'Hondt method, which is marginally less proportional than some other systems. The simplest implementation is the largest remainder method. Firstly theelectoral quota must be calculated, there are several ways to do this, but the simplest is the Hare quota, this is simply the total number of valid votes divided by the number of seats to be filled. So if there are 100,000 votes to fill 10 seats, then each candidate needs 10,000 votes to be elected. Then we divide the total number of votes each party received by the quota, and the party is allocated the the number of seats equivalent each whole quota it has received. For example if there are four parties, Red gaining 28,000, Blue 34,000, Yellow 31,000 and Green 7,000 votes respectively. Red gain 2 seats (2.8 quotas), Blue 3 seats (3.4 quotas), Yellow 3 seats (3.1 quotas) and Green 0 seats (0.7 quotas). Only 8 seats have been filled, so now we look to the largest remainders for the four parties. Red has a remainder of 0.8, Blue 0.4, Yellow 0.1 and Green 0.7. So Red gains the first of the two remaining seats, and Green the second. The election result is Red 3, Blue 3, Yellow 3, Green 1.

There is also a distinction between open and closed list systems. In the UK European elections are fought on a closed list system, which means that the order of candidates on the list is determined by party officials and voters simply vote for a political party, so in UK European elections voters can only choose between parties and not candidates. This provides party officials with plenty of patronage to hand out. Most parties can expect to gain at least one seat, and so being at the top of the list is equivalent to holding a safe seat. This encourages party loyalty, which is the purpose of patronage. On the other hand in Finland elections are always conducted on open lists. Although the party still decides which candidates are included on the list, it is the voters that decide the order of candidates on the list. Voters choose one candidate from a party, the vote goes to the party, but the candidate also receives a vote on the party list. The candidate with the most votes from people who voted for the party is placed at the top of the list, and is therefore elected first, as long as the party elects one person, it will be the person at the top of the list. Open lists dramatically reduce party patronage, although it is still the party that chooses who goes on the list.

List PR is an extremely versatile electoral system, it can work with large or small districts.Finland has 14 districts (excluding Åland) that vary from 32 members (Uusimaa) to 7 members (North Karelia). The whole country can even be one single electoral district, as in Israel. Voting is easy, either a vote for a single party or a single candidate. It usually produces very proportional results. When a high electoral threshold is applied to parties in list PR (that is, when parties are forced to gain a high percentage of the vote before they are entitled to elect members), it can be much less proportional.

Mixed Member PR (MMP)

The system used for the German Bundestag, the Welsh Assembly and the Scottish Parliament. It can be thought of as a special case of List PR. In this case not all elected members are drawn from the list. The list region is also sub-divided into UK style single member plurality (SMP) voting districts. A proportion of the representatives are elected by SMP, and the remaining members are drawn from the list. Voters are given two votes, they vote for a candidate in the SMP portion of the election, and vote for a party in the list portion of the election (all current MMP elections are from closed lists, though there is no reason why open lists could not be employed). This is done so that the final assembly is proportional, parties that have members elected from the plurality portion of the election lose list seats. So a party that meets or exceeds its electoral entitlement will elect no list candidates at all. For example in the Welsh Assembly election of 2007 the Labour Party won all seven SMP seats in the region of South Wales West, and so elected no list candidates whatsoever. It is instructive to note that the Labour Party was only entitled to six Assembly Members (AMs) for the region based on it's vote share, the fact that it gained all seven SMP seats means that it has an overhang seat. This is a systemic problemwith MMP. In Germany the a party would be allowed to keep it's overhang seats, but the list would also be completed in full, this means that the Bundestag can vary in size from election to election. In Wales this is not the case, whereas Labour was allowed to keep it's overhang seat, the Conservatives failed to elect a list AM that they were entitled to because the size of the Assembly is not allowed to vary, and SMP elected AMs take precedence over list AMs

The proportionality of MMP is also influenced by the proportion of top up members. The Bundestag is 50% SMP elected and 50% list elected, making it a truly proportional body. On the other hand the Welsh Assembly only has a 33.3% list element (20 out of 60), the Welsh Assembly can therefore at best be thought of as semi-proportional. For example the Conservative Party in Wales actually received more votes than Plaid Cymru in the 2007 Assembly elections, but Plaid gained more seats as the Conservatives lost out on the list portion of the election to overhang seats in South Wales East, South Wales West and North Wales. The proportionality of the Welsh Assembly could be dramatically improved by abolishing the regional lists and having a nation wide list. Labour managed to elect 2 list members from one electoral region, even though they were already over-represented from the SMP portion of the election, they would have received no list members had there been a national list. A further improvement would be to increase the size of the list portion to 40 members, and therefore the size of the Assembly to 80. A national list and 50% top up would produce a much more proportional Assembly.

Single Transferable Vote (STV)

STV is a preferential voting system, electoral districts are multi member and voting is by listing candidates in order of preference, as in the alternative vote. The main distinction between the alternative vote and STV is that constituencies are multi-member (an STV election in a single member district is simply an AV election) and that excess votes are transfered as well as votes from candidates that have been eliminated. Because there are multiple seats per constituency candidates from the same party are in competition with one another, just like in open list PR (but not in closed list PR). The big distinction between STV and list PR is that in STV a voter is able to transfer their vote between parties, the system is designed to reduce vote wastage and to elect the preferred candidate of the voter and not the preferred party, however the evidence from Ireland is that the overwhelming majority of voters vote a strict party line vote, making the vote identical to an open list vote. Variations on STV are used in Ireland, Malta, the Australian Senate (which has a very quirky version) and elections to local authorities in Scotland. In 2004 the Richard Commission recommended that the Welsh Assembly be elected by STV.

Once voting has finished and the votes counted the electoral quota is calculated, just like in largest remainder list PR. If a candidate reaches a quota of first preference votes then they are immediately elected. If no candidate reaches the quota, then the candidate with the lowest number of votes is eliminated and their votes redistributed.

When a candidate is elected their excess votes are redistributed. For example if the electoral quota is 10,000 and a candidate gets 15,000 first preference votes, then they are elected and the 5,000 excess votes are redistributed to second preference candidates. There are several ways that second preferences can be redistributed. For example in Ireland it is simply a random sample of 5,000 votes from the 15,000. Another way is to transfer all 15,000 votes at a rate of 1/3 of a vote each.

This elimination and redistribution of votes continues until all open seats are filled. If seats remain open with no candidate able to reach a quota, then candidates continue to be eliminated until the number of candidates remaining are the same as the number of seats to be filled.

One of the drawbacks of STV is ballot design. All proportional systems work best when electoral districts are relatively large, which allows for the election of smaller parties. Having large constituencies makes little difference to voting and ballot design in party list PR. But STV requires that the names of all candidates be printed on the ballot. So with a theoretical district of seven members, and five parties contesting it, this produces 35 candidates, all of who will have to have their names printed on the ballot, and a voter will have to find and rank all of those candidates they wish to vote for (though ranking does not need to be exhaustive). It would seem impossible for STV to have 32 member constituencies such as the Uusimaa constituency. It has been proposed that STV districts in the UK should be between 5 and 7 members. This would be something of an improvement on the situation in Ireland where districts are between 3 and five members. It is also a problem that the order of candidates on the ballot can affect the chances of election (fails to achieve independence of irrelevant alternatives) and STV, like all preferential voting systems can fail monotonicity (i.e. a second placed candidate can be eliminated before a third placed candidate, though it has been estimated that this would be very rare indeed). The newly invented variant CPO-STV seeks to remedy many of the shortcomings of STV.

Alternative Vote Plus (AV+)

AV+ is an electoral system invented by Roy Jenkins when he undertook his review into electoral reform in 1997/98, the Jenkins Commission. AV+ is very similar to MMP with a couple of good refinements and one deep flaw. Under AV+ the single member district (SMD) portion of the election would be conducted by the alternative vote, as opposed to SMP. This would mean that all SMD members would be elected on majorities. A further refinement of the system was the proposal to use open lists for the list portion of the system. Therefore the voter would be required to rank candidates for the SMD (AV) portion of the election, and choose a specific candidate for the list portion of the election. The flaw is the lack of real proportionality. Jenkins proposed a 15-20% top up element for the parliament, meaning that in a best case scenario only 130 members out of a parliament of 650 would be list members. This compares to 299 out of 598 (50%) in the Bundestag, 56 out of 129 (43%) in the Scottish Parliament and 20 out of 60 (33.3%) in the Welsh Assembly (which can be considered at best semi-proportional). It therefore follows that even a best case scenario 20% top up element would not produce anything resembling proportionality. Indeed the Jenkins Commission report estimated the results of the 1992 and 1997 elections if AV+ had been used as the electoral system, giving far from proportional results.

All electoral systems have good and bad points. There is no perfect electoral system. For myself I see no real reason to use MMP when the open list PR is available, you might as well elect MPs from the whole electoral region on a list rather than only half. Likewise for me AV+ is only really an option if 50% of parliamentarians are elected from the list portion of the election.

That leaves open list PR and STV. I really like STV, it's my favourite electoral system because it is so elegant. But on balance I tend to think it is not very practical. I'd like a system where our electoral districts are between 10 and 20, and that's not possible with STV. Because the electoral regions are so small (electing 3-5 TDs) in Ireland it has lead to the dominance of a single party for much of the last century, and there are only really two and a half effective parties in the Dail. On the other hand Finland with open list PR has a large number of effective parties and electoral regions are much larger, mostly between 10 and 20 members (though there is one much larger one and three smaller than 10, excluding the special case of Åland). It has three large parties that each gain 20-25% of the vote, and a couple of medium sized parties, including the Green League and the Left Alliance, both of which poll between 5 and 10% of the vote. There are 8 parties represented in the Finnish Eduskunta, compared to 6 parties in the Irish Dail. The Dail has 5 independent TDs, and STV makes it easier for candidates not affiliated to any party to get elected. But the distribution of votes and seats is much more skewed in Ireland than it is in Finland. The biggest party in Ireland, Fianna Fail, gained 41.56% of first preference votes, and ended up with 46.6% of the seats in 2007. The biggest party in Finland, the Centre Party, gained 23.1% of the votes, and ended up with 25.5% of the seats. This disparity may well be due to the small electoral regions of Ireland, and if Finland had many more small electoral districts, each electing between 3 and 5 representatives, Finnish politics might well produce a similar pattern. When one takes into account that in STV elections voters overwhelmingly vote a straight party line vote, this effectively turns the vote into an open list vote because the competition becomes between candidates within the same party vying for first preferences from party loyalists. On the other hand STV does give voters the option of transferring votes between candidates of different parties. STV has the big advantage that voters vote for individuals and not parties. On balance though I think an open list system would produce a more balanced parliament.

Alternative Vote (AV)

Gordon Brown's big plan for electoral reform is the introduction of the Alternative Vote (AV). Though Brown claims this is a reform of the electoral system, AV retains some of the deepest flaws of the plurality system.

AV is a type of majoritarian system, as opposed to a plurality system. Although districts (constituencies) remain single member, each member is elected by a majority of votes as opposed to a plurality. There are two basic types of majoritarian voting systems, a two round system (run off voting), in which elections are held in two rounds, and the Alternative Vote. In the two round system the top two candidates from the first round go through to the second round (usually held a week later). The French and Finnish Presidents are elected by this system. AV is a preferential voting system (as is the single transferable vote (STV) with which it shares many features), which means that voters rank their preferences, their favourite candidate is ranked first (1), their second favourite second (2) etc. If no candidate gains greater than 50% of first preference votes, then the candidate with the lowest number of first preference votes is eliminated, and their second preference votes redistributed. In the USA this system is referred to as instant run off voting. AV is used in elections to the Australian House of Representatives, and it would change the results of elections in some constituencies. For example take the case of John Howard (Liberal), the then Australian Prime Minister, in the 2007 election for the Division of Bennelong, Howard would have won the election under FPTP rules, polling 39,551 against TV presenter Maxine McKew's (Labour) 39,408. But McKew gained by far the greater number of transfer votes, especially from the Green Party, and won the election 44,685 against 42,251 for Howard.

The ERS estimate that the introduction of AV would increase Lib-Dem representation in the House of Commons, at least in the short term. But AV discriminates against small parties as much as the plurality system. For example Gordon Brown claims that AV allows voters to vote their conscience with their first preference vote, but in the Australian Federal election of 2007 the Australian Greens polled 7.79% of the vote and failed to win a single seat. Indeed of the 150 members of the Australian House of Representatives 83 are ALP members and 65 are Liberal/National coalition members (these two parties do not run candidates against one another and can be considered a single party from the point of view of psephology). Only 2 members of the Australian House of Representatives don't belong to one of these groupings. Compare this with the Australian Senate, elected by STV, where the Australian Greens hold 5 out of 76 seats.

One of the problems with the plurality voting system is the existence of safe seats. In the House of Commons about 60% of seats are safe, guaranteeing the MPs that represent those seats a job for life. This creates a patronage system, with the party having the power to de-select MPs that do not tow the party line, and providing a large pool of very loyal MPs for every party. AV does nothing to change that situation, most safe seats already give MPs in excess of 50% of the votes in elections.

AV is also likely to encourage parties to merge. If Lib-Dem votes are going to be transfered to Labour candidates anyway, then the voter might as well simply vote Labour. It is also obvious that, although all MPs would be elected with a majority of votes, many of those votes will be second, third or even fourth preference votes. In effect we end up in the same position as under the plurality system, with votes being case tactically.

In the end the conclusion has to be drawn that Gordon Brown wants AV because he believes that the Labour Party will benefit from Lib-Dem transfers more than the Conservative Party will. Gordon Brown has therefore attempted to subvert the goal of electoral reform to the interests of the Labour Party.

Plurality voting (FPTP) and proportionality

It is often claimed that FPTP is not a proportional system. Whereas this has been true in recent United Kingdom general elections, the plurality voting system can in fact produce proportional results. The United States House of Representatives is elected with a high degree of proportionality, but the price of this proportionality is a lack of real choice, only two political parties are represented in the US House.

The same is true of the House of Commons, during the 1950s when the Liberal Party was polling at 5% or lower, UK general elections were fairly proportional. Even in 1970 the Liberals only polled 7.5% of the vote. But there seems to have been a sea change in UK politics in 1974, with the Liberal Party polling 19.3% in the first election of that year, and 18.3% in the second.

The Gallagher Index is a way of measuring the disproportionality of an election. The higher the Gallagher index, the more disproportionate the election. When we plot the Gallagher index for all UK elections since 1945 against the third party (Lib or Lib-Dem) vote share of those elections, we see a clear correlation. Elections with a low third party vote share have a low Gallagher index (these tend to be elections before 1974). Elections with a high Gallagher index have a high third party vote share.

When a third party gains a large proportion of the vote it dramatically affects the disproportionality of a plurality election. This is because the winning party's share of the vote is much reduced, reduced to well below the 50% threshold that will normally give a majority. Or to put it another way, gaining 54.8% of the seats in parliament on a 49.7% vote share (as the Conservatives did in 1955) is significantly more proportional than gaining 55.2% of the seats on a 35.3% vote share (as the Labour Party did in 2005).

Ever since the 1970s the UK electorate have voted in large numbers for the third party (varying between 15% and 22% of the vote). The electoral system is fundamentally biased against third party voters, routinely disenfranchising them. In 2005 it cost 26,860 votes to elect a Labour MP, 44,306 votes to elect a Conservative MP and a whopping 96,482 votes to elect each Liberal-Democrat MP. This means that relative to Labour 4.3 million Liberal-Democrat voters are disenfranchised (or 72%).

It's time for our electoral system to reflect fairly how people cast their votes, and to stop this discrimination against third party voters.

Why FPTP (plurality) system favours Labour

David Cameron likes to say that first past the post (or more accurately the plurality voting system) favours Labour because Conservative seats have, on average, larger populations than Labour seats. To some extent this is true, it's down to demographics. Labour does well in Towns and cities, and these are becoming depopulated over time. Constituencies are drawn in 10 yearly boundary reviews from data collected from the electoral register. That means that the new constituencies that will be used in 2010 are derived from data that's already out of date. It means that the average Conservative constituency contains about 6,000 more people (not voters) than the average Labour constituency. Cameron wants to equalize constituencies and have less MPs. But that's not the whole story, the Electoral Reform Society (ERS) with Conservative Action for Electoral Reform (CAER) concluded that even with equally sized constituencies then Labour would still have gained a majority in 2005.

So what is going on? Well two things according to the ERS and CAER.

Vote Distribution

Labour has a more efficiently distributed vote. In constituencies in the south of England it is the Liberal-Democrats who are the Conservatives main threat, not the Labour Party. (e.g. see Eastbourne and Winchester). The Labour Party does not receive large numbers of votes in these constituencies. Conversely the Conservative Party and the Liberal-Democrats rack up large numbers of votes in the south in constituencies that they don't win. This is particularly true of the Liberal-Democrats. On the other hand in seats in the industrial north it is the Conservatives and Labour who are most in contention. (e.g. see Battley and Spen and Dewsbury). So the Conservatives rack up a lot of votes in the north without electoral succes, while the Labour party don't have the same problem in the south (though the Liberal-Democrats and the Tories do). Essentially the Labour vote is lumpy, it is concentrated in certain towns and cities, whereas the Conservative and Liberal-Democrat votes are thinly spread.

Turnout
According to the ERS and CAER, in 2005 turnout was a very big factor in Labour's majority. The average Conservative constituency was already about 9% bigger than the average Labour constituency. This was not enough to change the election result. But in 2005 the average turnout in Labour constituencies was 58% compared to 65% in Conservative constituences. The effective size difference between Labour and Conservative constituencies was therefore nearly 23%. 47,618 people voted in the average Conservative constituency compared to 38,739 in the average Labour constituency. Labour therefore needed a lower number of votes to win seats.
Clearly the dual problems of vote distribution and turnout cannot be addressed by David Cameron's commitment to equalizing constituency size and decreasing the number of constituencies. In fact having larger constituencies will simply mean that Liberal-Democrat votes are squeezed even more.
Full report: The Conservatives and the electoral system

Jonathan Friedland talking sense in the Guardian.

Reading Jonathan Friedland's piece "This could be a blip. But if not, British politics will be changed for ever", we finally some sense from a journalist. I'm a little bored with Guardian journalists writing that a big LD vote will make no difference to parliament or politics.

Brown and Cameron can't have it both ways. They have to accept that when the electorate give a result that is unique in recent years, then that is still a valid result.

People want a hung parliament. PR is likely on the way if the LDs get ~100 seats and hold the balance of power.

In the end it's a red herring for the Tories to say that Cameron should be PM if he gets more votes than Brown but has less seats. Cameron is in favour of FPTP, so he more than anyone should accept it's inconsistencies. If Labour get the most seats then the normal process would be for the head of state to ask him to try and form a government. In doing this he has the right to make a minority government work, or to try to negotiate a coalition with the LDs.

If he fails then normally Cameron would try to form a government, again he'd probably end up negotiating with the LDs.

But these negotiations are a give and take situation, they will not be able to demand that the LDs support their government, and give nothing in return, especially if the LDs end up with a 30% voteshare and are only a couple of points behind the Tories.

That probably means that the LDs will demand PR, and that means that the Labour or the Tories will have to negotiate that point.

It doesn't necessarily mean STV (though I'd like it). But it will mean introducing a proportional system that the LDs coalition partner can live with. I'd be happy with MMPR or open lists or STV myself.