In one respect, the decision by Afghanistan's electoral commission to delay parliamentary elections is regrettable. Regular elections are, or should be, an essential part of democracy.

In almost every other respect, though, the delay is positive. It shows that realism has replaced idealism. It shows that President Karzai and his Western backers have learnt lessons from last year's botched presidential election. And it shows a general recognition that electoral changes are needed before voters are called again to the ballot-box. A new date has been set by which the elections must be held – 18 September rather than 22 May – which could spur on the reform process.

The announcement removes one potential stumbling block from the London conference on Afghanistan later this week. Not only is the question of the election off the agenda, but the country's electoral commission has admitted that shortage of money, security problems and what it called "logistical challenges" combined to force the delay – which suggests that Afghan leaders may be ready to accept more responsibility for addressing their country's plight.

This is precisely what the US, Britain and other countries with forces in Afghanistan are hoping for. Unless President Karzai, his government and the Afghan army can grow in strength and carry more conviction with their people, the exit strategy set out by President Obama after a succession of reviews last year risks being strung out for many years, or even thwarted altogether.

Still, the achievements of the London conference are likely to be modest. Conducted at foreign minister level – under the chairmanship of Gordon Brown and the UN Secretary General – and limited to one day, it will probably not produce any grand new departure. The best result would be a set of objectives, focused on reconstruction, and a timetable, on which Afghan leaders and this large swathe of the international community can publicly agree. With public support for the Afghan enagement waning in both the US and Britain, the task for Mr Karzai and his Western backers will be to convince doubters that continued outside involvement is worthwhile.