The Liberal Democrats were always going to sell someone out. It’s not really a surprise that it was students. Explaining why the Liberal Democrats may seem like a good party to vote for has long been tricky for anyone involved in another party. Using the privilege of perpetual opposition at Westminster, Liberal Democrats were able to create a policy platform with a very wide appeal.

Not content with being the natural party of small farmers in the Scottish Highlands (who’ve always voted Liberal), Liberal Democrats created policies to court huge swathes of society. The aim was to build up ‘vote banks’. These vote banks would then yield the votes that could turn the Liberal Democrats into a party of government – albeit as a minor partner.

And vote banking turned out to be very successful. From winning only 11 (Liberal) seats in 1979 on 13.8% of the vote, Liberal Democrats took 62 seats in the 2005 election on 22%. This was based on vote banking and ‘community politics’ – dealing with small issues that were important to local people, such as potholes or dog mess. By bringing together various groups of voters Liberal Democrats were able to win constituencies.

Community Politics: Liberal Democrat Alan Dean pointing to a pavement, thanks to Glum Councillors blog

The techniques used to build vote banks included the “penny on income tax for education” to appeal to parents and teachers. Opposition to the Iraq War appealed to British Muslims and anti-militarists. The commitment to abolish tuition fees appealed to students. And a local income tax was proposed to replace Council Tax, freeing pensioners from local taxation and creating another vote bank. These allowed Liberal Democrats to build winning coalitions in a wide range of constituencies.

The process of vote banking took place at a time when ideology was on the wane. This allowed Liberal Democrats to assemble a coalition that was, in many areas, free from ideology. What ensued was a range of campaigns and policy positions designed to take advantage of political opportunities.

While these policies were undoubtedly sincerely held by sections of the party, for others they were designed to ensure electability. And the policies were bundled together with an explicit message that Liberal Democrats weren’t like other politicians, they were honest and trustworthy. They didn’t break promises. So far so good.

But there was a huge problem with this. For the Liberal Democrats to win in seats like Richmond Park in wealthy West London, or leafy Edinburgh West they needed to appeal to different groups of voters to those that elected them in student-filled Manchester Withington or Bohemian Hornsey and Wood Green in London. And that’s before you consider the rural seats Liberal Democrats hold. This worked while Liberal Democrats were in opposition, but it was guaranteed to come crashing down once they entered government at a time when money was tight.

Of course the Liberal Democrats made things substantially worse for themselves by joining a Conservative-led coalition hell bent on making massive ideological cuts. They then exacerbated an already bad decision by going along with (and sometimes even championing) those cuts. This made the difficult task of retaining credibility in government almost impossible.

Once it became clear that when Nick Clegg said “Say Goodbye to broken promises,” what he meant was “I’ll break promises as is necessary to cosy up to the Tories.” Liberal Democrats claimed to be different to ordinary politicians; they claimed they wouldn’t go back on their word. They then spectacularly went back on their word on one of their most distinctive policies. This meant their climb-down went beyond the policy at hand – it became an issue of trust. The Liberal Democrats showed not only that they didn’t care about students, but that they couldn’t be trusted to keep their promises.

Government is, of course, very different to opposition. It’s very difficult to please everyone while in government. You have to make decisions that demonstrate your priorities. And when there’s not much money that sometimes means you can’t deliver for one of your vote banks. Students were always the most likely to bear the brunt of this. A low electoral registration and turnout rate and the widespread perception that young people were apathetic meant if one vote bank had to go, it was always going to be students.

But the Liberal Democrats can’t be held to blame for this. To win lots of seats in an un-proportional system any third party will have to create these vote banks. For the Liberal Democrats to win outside their heartlands in rural Scotland and Wales they needed to build a broader coalition. That coalition was always going to include some groups that couldn’t hold together through a period in government.

And this is significant beyond the Liberal Democrats. It shows that the temptation to be opportunistic, to stay in the centre and to vote bank cannot carry a party successfully through government. This is particularly true when that party is a small party. But even the Democrats in the United States have found that building a centrist coalition is very difficult as President Clinton would certainly have attested to. Much better to have build a stronger base in social movements. They needed to change the political culture, rather than pandering to different and mutually exclusive vote banks.

While it seems like the Liberal Democrats are likely to follow their Australian sister party out of parliament, the temptation to replicate their approach to politics should be avoided. Many Greens will be keen to win the votes of disaffected Liberal Democrats. But mimicking Liberal Democrat techniques will only lead to the same electoral suicide as the Liberal Democrats are about to suffer.

It’s right that Greens should appeal to some of those Liberal Democrat voters. The way to do that is to take firm positions on issues. It’s to make clear what we stand for, and to make sure we don’t end up in a position where we’ve over-promised in an attempt to be popular. Tricking the electorate by saying that you’re in favour of things that you’ll abandon once in power is a dead end strategy. Similarly centrist opportunism will result in wipe out, sooner or later. To borrow a phrase, those who keep to the middle of the road get run over.

Greens must build a movement, we must change the political culture. And most of all we must avoid falling into the trap of populist issue-following. It isn’t working for the Liberal Democrats and it won’t work for Greens.

At the heart of that must be offering leadership to the student vote. There are thousands of student votes there for the taking, and our approach must be to prioritise the Green principle of free education. And we must never waver from that stance, or the fate of the Liberal Democrats awaits.