At last, Nick Clegg is emerging as a serious-minded leader of substance. The Lib Dem conference in Harrogate at the weekend could have been so different. Six months ago, after a messy and scrappy conference that left many of us in despair, shadow education minister Stephen Williams was confidently informing the THES that the party would be abandoning its policy to scrap tuition fees. The implication of this interview was that we were set for a bloody big row – arguably the biggest one we have had since the messy formation of the party between 1989 and 1991. I'm not the only one who was seriously questioning whether I had the energy for it all.

Yet so much has changed over the past six months. The collapse of the banking system and the realisation that we were headed for economic collapse has rendered the divisive and thoroughly inconclusive tax debate we had in Bournemouth a curious echo of a different political era. The party's response to the government's VAT cut masterminded by Steve Webb put the focus back on traditional Lib Dem territory by proposing a massive investment in infrastructure designed to cut fuel poverty, cut carbon emissions and create jobs. And then in January, the party's policy committee voted overwhelmingly to extend our anti-fees policy to part-time students.

Nick Clegg's early weakness for attention-grabbing gimmicks has been superceded by a new seriousness of purpose by a leader finally finding his voice. He has been rewarded by a small but perceptible shift in the polls. The talk a few months ago was of a Tory landslide and a Lib Dem wipeout, yet it has become increasingly apparent that Clegg may find himself holding the balance of power after the next general election. That is both a massive opportunity for the party and a massive risk. Fevered speculation about who the party is likely to deal with rarely works in our favour, yet equally if we aren't in politics to change things then what is the point?

Sunday's leader's speech was deliberately low key. Starting by paying tribute to the soldiers killed in Northern Ireland the night before, Clegg's speech was notably free of jokes (even if he did allow himself a few self-deprecating one-liners) and focused almost exclusively on the economy. But this speech was far from being all doom and gloom. Citing the examples of the Beveridge Report and Sir Christopher Wren's visionary drive after the Great Fire of London, the emphasis was on using this crisis as an opportunity to build a better society instead of simply wanting to go back to what we had before. This may sound like motherhood and apple pie, but this message of hope contrasts wildly with the Labour government's panic-driven response to the crisis (all bail-outs and fiscal stimuli) and the Tory decision to hide under a table and leave the market to sort it all out.

One theme that Clegg has been actively developing over the past few months is to point out how our boom and bust economic system is integrated with our boom and bust political system. If you want an end to the former, you need to sort out the latter. Yet this is an issue that neither Labour nor the Tories are prepared to pay more than lip service to. As such, what he presented on Sunday was the beginnings of a meaningful party narrative. If he is allowed to develop this further, and can fight off the troglodytes in the party who would want to see him abandon any pretence of analytical thought in favour of yet another vacuous 10-point-plan (Charles Kennedy's big mistake in 2005), then things could get very exciting for the party indeed.

There is still more work to be done. I still think we need to do more about social justice and child poverty; improving education and tax cuts on people with low incomes is certainly necessary but not sufficient. But if Nick Clegg can maintain this new sense of purpose, then the party has every reason to be optimistic about the future.