I almost had an article published on the Guardian’s Comment Is Free website on Wednesday, marking the launch of the Lib Dem manifesto. For convoluted reasons it never saw the light of web – but most of it stands the test of time. Except perhaps the line suggesting the party could never hope for Nick Clegg to be as well liked as his predecessor: that’s the power of television for you.

Quite rightly, many wise (and not necessarily old) heads have been counselling caution following the last 24 hours explosively positive headlines for the Lib Dems. The party has enjoyed polling spikes before – most notably after by-election triumphs – and they have proven to be short-lived episodes. There are two debates, and three campaigning weeks, still to go. We must ‘keep calm and carry on’.

But it’s also right to note how much more professional (in its best sense) this campaign is than before. That’s not just about Nick; there’s a whole team in Cowley Street who deserve credit. There is a clear narrative: the Lib Dems stand for a fair society. There are four easily memorised policies which link to the narrative and talk directly to voters’ concerns. The party has gained good press with a manifesto that has united party members. There has been a genuinely good and innovative party election broadcast.

Whatever happens over the next 20 days – and a lot will happen, good and less good – the party has got its act together, and looked like a proper team serious about being in government. And at just the right time, too.

Anyway, here was my quick take on the manifesto …

The contrast with five years ago could not have been more acute. When Charles Kennedy launched the party’s 2005 election manifesto, his fumbling answer to our policy on local income tax dominated the news coverage. It came to symbolise in too many voters’ minds that the Lib Dems, however well-meaning, failed the seriousness test.

Fast forward to 2010, however, and a lot has changed – for a start, the party leader. Clegg may not (yet) be as nationally well known as his predecessor, and I doubt he will ever be held in quite the same affection as ‘Cuddly Charlie’. But what Clegg lacks in bonhomie he is making up for in credibility, with The Guardian’s Michael White noting his “impressive grip of detail”.

Though his two-year tenure as leader has not exactly been free of mis-speaking (that Piers Morgan interview, loose talk of “savage cuts”), on Monday Clegg faced the ultimate test – an interrogation by Jeremy Paxman – and passed with flying colours. Interestingly, it was revealed today that David Cameron has bottled out of a similar encounter, fearful it seems of being subjected to a Paxo stuffing.

But there has been a bigger change in the party than simply its leader. In 2005, the party campaigned on 10 disconnected key pledges – all important in their own individual way, but lacking a compelling ‘narrative’. Today the party’s manifesto was launched with four key messages: fair taxes, fair chances (education), fair future (economy and environment) and a fair deal (cleaning up politics).

The constant Lib Dem refrain of fairness is no accident. It is the natural follow-on from a very deliberate strategy set out by Nick Clegg in an important Demos pamphlet he authored last year, The Liberal Moment, in which he located the party firmly within the progressive liberal tradition: the enemies of conservatism, and rivals to Labour.

By emphasising the Lib Dems’ commitment to fairness within society, the manifesto serves notice of the party’s aim to displace Labour as the natural choice of progressive voters.