This week it is five years since I was elected leader of our party. It feels at once like it was yesterday and a lifetime ago!
The announcement of the result and my acceptance speech all passed in something of a blur. The memory that really sticks in my mind is of the next day, when I visited a school in Simon Hughes' constituency.
I remember one of the students asked me what I'd do if I became Prime Minister - "theoretically of course" he added, hurriedly. And he was right: I've only got as far as Deputy. But we have as a party absolutely defied the expectations that were set for us five years ago.
They said we would be wiped out at the election. They said we couldn't be trusted with the economy. They said we were a fringe party only interested in fringe issues.
We've proven none of that is true. We've proven we can govern, and govern well, even at a time of upheaval and crisis for Britain. We've proven we're committed to delivering a stronger economy and a fairer society enabling everyone to get on in life.
But most of all we've proven that Liberal Democrats can anchor a government in the centre ground, moderating the forces of tribalism that you would expect to dominate politics at a time like this.
I believe Britain needs that moderating force more than ever. That's the argument I made in a speech this week to mark my anniversary and set our course for the rest of this Parliament.
I won't try and repeat the whole speech in this letter. You can read it here or watch the video.
But there's one example I used that I want to repeat - because I think it shows exactly what I mean by "anchoring" the Government in the centre ground. It's an example of how the very fact of coalition means positive compromise - it means reasonable ideas go ahead and extreme ones fall by the wayside.
This autumn the coalition decided to go further to reform benefits to help support people back into work and reduce the costs of the welfare state. That's the right thing to do.
The Conservatives suggested we cut an extra £10bn from welfare, take away child benefit from families with more than two children and take away housing benefit from everyone under the age of 25.
But when our two parties sat down to agree a plan, instead the coalition stuck to the centre ground. We agreed to increase benefits by 1% a year, in line with public sector pay rises - not freeze them - delivering savings of just about a third of the proposed £10bn. And we rejected completely the more extreme reforms that had been put on the table, protecting young people and larger families from cuts.
So if you're asked what Liberal Democrats are doing in Government - tell this story. Welfare reform is important to reduce the deficit and help get people into work. But if you want reasonable welfare reform, not indiscriminate welfare cuts, we're the party you want on your side.
But that's enough from me. Enjoy Christmas and don't spend too much time talking about politics!