Liberals have been champions of political reform since the formation of our party more than a century and a half ago.
House of Lords reform, party funding, devolution - and of course, reform of the voting system.
It is no surprise then that this Coalition government is determined to be a radical reforming government, particularly when it comes to changing politics.
Right now, the British people are finally getting the opportunity to have their say on how the MPs who represent them are elected.
Today I want to explode some of the myths being propagated by the opponents of AV; explain why I think first past the post needs to go; and describe the political challenge of facing down vested interests in order to deliver liberal reform.
First, though, I'd like to briefly remind you of the background to the current debate. When the expenses scandals were exposed nearly two years ago, a long-standing erosion of faith in our political institutions erupted into a full-blown crisis.
It became clear that the distance between people and their representatives had grown into a divide big enough to threaten the legitimacy of parliament.
When the stories of duck houses and moat cleaning hit the front pages, apathy and resentment turned into anger.
And rightly so.
As we decide, as a nation, on whether to keep first past the post or move to an AV voting system, it is important to keep in mind that we have a political crisis in Britain to match the financial crisis that threatened our economy.
Switching to a fairer system will not fix all of our democracy's ills overnight. I don't expect the first parliament elected under AV will be full of MPs with the wisdom of Pericles and the virtue of Lincoln. But it will be a strong start to the job of cleaning up politics.
The Alternative Vote addresses some of the deepest problems in our current system.
It means all MPs will have to try to win the support of a majority of their constituents instead of relying on their core vote.
It means they will have to engage with people who are not their core supporters, listening to a wider range of views and bringing more people into the democratic process.
It will help to reduce the complacency of MPs with jobs for life in safe seats.
AV simply updates our voting system to give people more power, and more choice.
But as with almost all changes that give people more power and more choice, paternalists and conservatives are lining up to try and block it.
Let me quote from the excellent IPPR report published this week: "FPTP is a system designed for an age of political tribalism which no longer exists. AV suits the electoral conditions prevalent in Britain today - particularly the shift to multi-party politics."
First Past the Post is like a black and white television with two channels in a multi-channel HD world. It's time to move on.
The No campaign seems less interested in making the positive case for First Past the Post than attacking a ludicrous caricature of AV.
The arguments being used against AV fall into two equally flawed categories - distractions and falsehoods.
The first distraction is that this vote is in some way about the coalition. No it isn't.
This is a strong coalition, forged at a time of crisis.
We must not forget the circumstances that brought this coalition together.
An election result that gave no party a majority at a time of deep economic crisis.
In the days before and after the election we watched as Greece descended into turmoil because of a sovereign debt crisis that could easily have spread to Britain if the financial markets lost confidence in us.
But while our decisive action has reduced the risk, it has not disappeared.
We have kept the wolves from the door, but they are still lurking in the woods.
If the coalition were to falter now the crisis we have worked so hard to avoid would threaten the nation again.
The work of this government will continue in the national interest regardless of the result of the referendum.
Some people act like there isn't a threat.
It might seem invisible but the truth is that today, yesterday, tomorrow, and every day of every week we are borrowing £400m.
£400m a day borrowed on the backs of future generations. Enough to build a primary school every 20 minutes.
To deny that is an act of political cowardice.
In Labour's case they are going round the country pretending they wouldn't make these decisions when their own plan, the Alistair Darling plan, was to cut £14bn this year compared to the £16bn we are cutting.
For every £8 we are cutting they would cut £7.
To deny that reality is to treat the British people like fools.
The second distraction is that AV - and by implication coalition governments - result in "broken promises".
The truth is this: If we want a different kind of politics, one in which parties can work together in the national interest, we all have to grow up a bit.
Let me be candid. It is indeed true that the Coalition Government is not delivering the whole Lib Dem manifesto.
But that's because I'm the leader of a party with 57 MPs out of 650.
I know it's unfashionable for politicians to admit the limits of their electoral success, but the fact is the Liberal Democrats came third at the General Election.
If people want more Liberal Democrat policies the way to get them is to elect a majority Liberal Democrat government.
That didn't happen.
In the meantime, I will continue to make what are sometimes difficult compromises, but ones which are always shaped as best I can by the Liberal values I hold dear.
Coalition government is a new concept in modern Britain, but it works on the basis of very British values.
It means discussion, debate, compromise and the search for common ground, regardless of your political starting point.
It means putting aside dogma and tribalism and searching for a way forward that most people can accept.
Who doesn't, in their daily lives, find themselves working together with people they disagree with?
What's more, it can produce better results.
It means long-term solutions instead of short-term calculation.
Look at some of the issues this government has been able to tackle by bringing two political parties together.
An economy teetering on the edge of a cliff.
A chasm between the richest and the poorest in our society that stunts social mobility.
A welfare system that breeds dependency, fuels a culture of worklessness and entrenches disadvantage over generations.
A political crisis that undermines our democracy.
These are not easy things to tackle and the controversy caused in doing so may well have forced a single party government into half measures and headline-chasing initiatives.
And we can't afford that, especially in the financial crisis we find ourselves in now.
There are people on the left and the right who preach new politics and pluralism and yet are now so damning of its inevitable consequence, which is compromise.
You can't claim to stand for a new kind of politics, for a new kind of pluralism, and then vilify those who try to practice it.
And then there are the three falsehoods.
First, the No campaign claims that AV will somehow help extremist parties like the BNP.
What astonishes me most about this claim is the brazen way it seeks to reverse the truth.
AV will make it harder for extremist parties to get elected because it favours those who can appeal to a majority of voters in a seat.
It is First Past the Post that allows MPs to be elected with just a fraction of the vote.
Nick Griffin knows this, which is why he is campaigning for a No vote.
You don't have to take my word for it, in the words of the BNP's deputy chairman Simon Darby:
'We are never going to get our feet under the table under the AV system.'
They say you can judge someone by their friends.
You can judge a voting system by its friends too.
The friends of First Past the Post include the BNP and the Communist Party.
And the friends of AV are the Liberal Democrats, the leader of the Labour Party, the Green Party, UKIP, SNP, Plaid and so many people beyond politics.
The second falsehood is the claim that AV will lead to more hung parliaments.
While there's no way of knowing the outcome of future elections, it is worth looking at the example of Australia, which has used AV for 90 years. I know we have a distinguished Australian scholar on voting systems [Anthony Green] with us today, so I won't venture too detailed an opinion on its operation there. But it is worth noting that in Australia they have had fewer hung parliaments than we have.
And of course this Coalition Government was the result of a hung parliament following an election carried out under First Past the Post.
The third falsehood from the No campaign is that switching to AV will mean bringing in new, expensive counting machines.
This is simply untrue. There are no plans to bring in electronic machines. We won't need them. It won't happen.
This is the first time British people have ever had a choice on how to elect their MPs.
They deserve a debate based on reason and reality, not prejudice and misinformation.
Of course this referendum is only one part of a broader Liberal agenda of reform.
Earlier this month, nearly 900,000 of the poorest workers were lifted out of paying Income Tax altogether, with hundreds of thousands more to follow them next year.
More than 20m people on low and middle incomes have received a £200 cash tax cut.
We have ensured that pensioners will get a meaningful rise in their state pension every year. Someone retiring on a basic state pension this year can expect to get £15,000 more over their retirement than they would have under Labour.
The biggest lift in the state pension since Margaret Thatcher broke the earnings link back in the 1980s.
Our Pupil Premium, rising to £2.5bn a year by the end of this Parliament, means more money for schools targeted at the most disadvantaged, which in turn will help every pupil, every school and every community.
We are creating more apprenticeships than Britain has ever had before - a quarter of a million more by the end of the parliament.
We are restoring the civil liberties that Labour took away, starting with scrapping ID cards, the National Identity Database and 28-days detention without charge.
We have ended the disgrace of child detention and brought a dose of sanity to our immigration system.
We are giving people the right to recall MPs guilty of gross misconduct.
We are reforming the House of Lords after a hundred years of politicians saying they will, and doing nothing.
And, yes, we are giving people the chance to choose a fairer voting system that will bring more accountability and more democracy to our politics.
Let's be clear about the choice before us.
AV is not revolutionary. It is an improvement on First Past the Post. An update to our democracy.
It is a small change that will make a big difference.
The strength of AV is that it goes with the grain of Britain's traditions.
We don't go for big revolutions. We gradually update the way we do things to make sure we keep up with the times.
It is evolution, not revolution and it has served us well throughout the centuries.
AV is a very British reform.
The world will not stop turning on its axis when people put 1-2-3 on a ballot paper instead of a cross.
If you only want to vote for one person, you can. It just gives you more choice.
AV is already widely used.
A form of AV is used to elect the Mayor of London. It is used to elect trade union officials and charity board members.
It is even used to elect the leaders of the Labour Party and the Conservative Party.
It is used to select Conservative candidates.
If it is good enough for the Conservative Party why don't they think it is good enough for the rest of us?
Attack on First Past the Post
And when the No camp attack change, it is worth looking at what they are defending.
This is a referendum on First Past the Post just as much as a referendum on AV.
First Past the Post is an outdated system propping up a failed establishment.
It means MPs elected by a fraction of their constituents.
As a result of the last election, most people are represented by MPs that most people did not vote for.
It means politicians and parties fighting for the votes of a few thousand people in marginal constituencies and ignoring millions of others.
Where is the fairness in that?
Where is the democracy in that?
What are they so afraid of?
What have they got to lose?
The answer is they are afraid of change.
Change which would loosen their grip on power they no longer deserve.
When the vested interests of the old, tired establishment of politics and the media are so opposed to a reform - turning so personal about it - you know there is something worth fighting for.
It is the attack on people working together for the national good that is so dismal.
It is a desperate attempt to defend the indefensible - the old politics of tribalism backed by dinosaurs on all sides of the political spectrum.
If you think the political establishment has served you well, then I encourage you to vote for First Past the Post.
If you think the political establishment has let you down, become complacent and taken you for granted, then support the Alternative Vote.
One of the things I've learned in Government is that taking on vested interests is not a task for the faint-hearted.
The people defending the status quo, and a status quo that suits them, will not give up without a fight.
This includes the MPs in Westminster opposing voting reform that threatens their safe seats.
But also the Lords clinging to their unaccountable powers.
The political party machines, scared of voting reform.
The financiers in the City of London, resisting fairer regulation and transparency.
Old fashioned companies resisting any efforts to give parents more time off to care for their children.
And as I learned recently, even challenging the closed shop nature of internships provokes plenty of controversy.
Liberal policies, by definition, challenge the status quo. They unsettle existing patterns of power and privilege.
The AV campaign is simply the latest example of that.
When people with vested interests are threatened, the louder they will shout and scream. We can't let them stop us.
With so much deception and misinformation around, we should look at what will happen if we switch to the Alternative Vote.Candidates will simply be forced to appeal to a majority of voters in their constituencies instead of relying on their minority of dedicated followers.Political parties will have to campaign across the whole country and not just the small number of marginal seats that currently decide elections.Politicians will have to work harder for your vote instead of taking you for granted.
This means more voices will be heard, more opinions listened to, and more legitimacy for the winner.
That can only be good for our democracy.
It is time to reject the status quo that has served us so badly.
It is time for real change.
It is time to make our democracy better.
It is time to say Yes to fairer votes.