This year marks the 30th anniversary of Margaret Thatcher's landslide, after which serious political commentators, including those writing for the Observer, speculated that Labour could never win again.

In March, we will observe the 10th anniversary of the invasion of Iraq, an illegal act by the Labour government, which was supported by the then Conservative opposition. The Tories managed to combine extremism with irrelevance; they subsequently found themselves in third place in the polls, written off by most pundits as incapable of ever governing again.

We will also mark the 25th anniversary of the acrimonious merger of the Liberals and the SDP, which formed the Liberal Democrats. After the chaos of the merger process, the Liberal Democrats were dismissed as doomed by anyone who knew anything about politics, especially after a poll in the Observer recorded a historic 0% for the Lib Dems.

The Liberal Democrats of today are subject to similar apocalyptic predictions. Those who foresee our demise are just as likely to be proved wrong as those who wrote off Labour, Conservatives and Lib Dems in the past.

The Liberal Democrats are gearing up for our toughest general election in a generation. Our preparations are ahead of our opponents and our focus is relentless, as you might expect with Paddy Ashdown as chair of our general election campaign. History may have proved political pundits wrong up to now, but we are taking no chances. We will defend our 57 seats tooth and nail and audaciously take the fight to the other parties in seats we intend to gain. We will have a unique message: the Lib Dems are the only party able to deliver both a strong economy and a fair society.

We hear siren voices from the Tory right saying that the answer to the borrowing crisis is for gratuitous cuts beyond what is necessary, including £10bn in welfare cuts. We said no and we stopped them. To cut more now would be cruel and counterproductive; it would hurt the most vulnerable and it would derail the recovery. We also hear siren voices from Labour saying that the answer to the borrowing crisis is to borrow much more – we say no to them too. This would lead to a weaker economy, higher interest rates, house repossessions and huge rises in unemployment.

After 65 years in the wilderness, the Liberal Democrats found themselves in government at just the right time for the UK. Our economy was on life support and our society increasingly unfair. In coalition, the Liberal Democrats have focused on rescuing the economy from meltdown, while ensuring that our recovery is fair. Our flagship achievement of cutting income tax for ordinary people by raising the threshold at which you start paying income tax has both boosted spending in the economy and made our country fairer.

A party with a platform of demonstrating both competence and compassion is in a unique position in British politics.

Labour's record of economic incompetence strikes fear into millions of citizens on low and middle incomes, who know how much their future depends on a strong economy. Equally, the Conservatives have a record of favouring the richest people in society at the expense of pensioners, people who find themselves on benefits and those working hard on salaries that barely cover their outgoings.

In the Liberal Democrats, voters have an option that can outshine Labour on economic competence and shame the Tories when it comes to fairness.

For the first time in decades, Liberal Democrats will face the next election able to do more than just make promises – we will be able to demonstrate our achievements, too. This year, we will further increase our tax cut for low and middle earners, cutting income tax by £600 for 24 million people since 2010. Someone on the minimum wage will have had their income tax bill cut halved. We will also dramatically increase parents' access to childcare, so that it's easier for parents to get back into work. In 2013, we will reform the welfare system to get people trapped on benefits back into work. And we will continue to work to cut unemployment by creating tens of thousands of jobs across Britain in the new, green economy.

As I visit Liberal Democrat volunteers up and down the UK, I see a much happier crew than you might imagine if you believed everything you read in the papers. Did you know that the Lib Dems ended 2012 with net gains in local council byelections? Or that we received more money in individual donations than either Labour or the Tories in the last quarter? Or that our poll ratings are no worse than they were at the same point in the last parliament?

So, as we take note of certain political anniversaries in 2013, we also take note of the political pundits who wrote accompanying premature obituaries for one of Britain's three main parties.

The Liberal Democrats will spend 2013 working to build a stronger economy and a fairer society so that everyone can get on in life. We will also be preparing to confound the pundits' expectations yet again in 2015.