Ipsos MORI’s research over the past few general elections has shown that voters themselves placed more weight on the parties’ policies (46%, for example in 2005) than on the image of the leader (31%) or party image (23%) when deciding how to vote.

2010 was different. Even before the leadership debates, in February 2010 the public were giving equal weight to the importance of leaders and policies in their voting decision.

The question looking ahead is whether the increasing prominence of the image of the leaders represents a further “presidentialisation” of British politics, or if the circumstances of 2010 were unique?

One of the reasons for the higher weight given to the image of the leaders in 2010 was that none of the parties established an advantage on the issue that dominated the election – the economy.

If by 2015, either Labour or the Conservatives have a clear advantage on the issues that most people will vote on then we may see the importance of “issues” at the election rising again.

If not, and with the likely return of leadership debates at the next general election, then the image of the party leaders may again be crucial. By leader image we do not mean the hair style or the cut of their suits, but important characteristics such as the public’s view of their competence, belief in their understanding of the problems facing the country and the world, and confidence that they listen to the views of the ordinary person.

Mark Gill is former head of political research at Ipsos-MORI and co-author with Bob Worcester, Roger Mortimore, Paul Baines of Explaining Cameron’s Coalition