Most analyses of voting intention figures lately have focused on party share, or the gap between the Conservative and Labour parties, or other such ‘aggregate’ measures. However, to understand what is really going on in the polls at the moment, we don’t just need to know how many people are changing their minds, we need to know who they are.

The ‘Brown bounce’ may be receding, according to the polls conducted so far in September, after the sharp rise in Labour’s share of voting intentions over the summer months, while the Tories’ share of the vote slipped. The Liberal Democrats slid from an average of 17 per cent in May/June to as low as 15 per cent towards the end of August, hitting their core level of support of around 15 per cent. However, as of the second week of September, most polls still show Labour leading over the Tories, both in terms of vote share as well as satisfaction with individual party leaders. Gordon Brown’s personal satisfaction rating shows almost two people satisfied for every person dissatisfied, a much better ratio than David Cameron achieved even in his first few months as leader.

Comparing Ipsos MORI’s aggregated data from April/May to the data from July/August (skipping over the month of June during which the Labour leadership transition took place), there was an eight-point increase for Labour, with a four-point drop for the Lib Dems and three points for the Tories. In addition, mentions of other smaller parties decreased by three points. So the picture appears fairly straightforward: floating voters are moving away from all the parties and towards Labour.

Like so many things in politics, however, the true picture is far more complicated. For example, both Conservative and Labour shares of the vote are ahead of their relative strengths at the 2005 general election, indicating that both parties are in a stronger position than they were two years ago, and the Lib Dems in a notably weaker one. In addition, it appears that recent changes in reported voting intention differ greatly by gender and age.

The figures show that Brown’s bounce is due almost entirely to men’s increasing support for Labour rather than women’s; men’s swing from the Tories to Labour is 9.5 per cent and women’s just 2 per cent. This is likely to be related to both increasing dissatisfaction with Cameron as well as the fact that men rate the economy as a more important issue than women – and Brown is seen to have performed very well on the economy over the last 10 years.

While men’s support seems to be shifting away from the Tories towards Labour, women’s support is moving from the Lib Dems towards Labour. This group of women were likely to have voted Labour in 1997 and 2001, but found themselves disillusioned by the Iraq war and Blair’s promises on public services, and so shifted their support to the Lib Dems at the last election. Thus Brown’s bounce is actually a mix of women coming back into the fold after moving away from Labour in the early noughties, and men who were initially impressed by Cameron’s new approach and rhetoric (and were very ‘turned off’ by Blair), and who now look willing to give Brown a chance.

The breakdown by age provides an even more intriguing picture. Middle-aged people (35-54 year-olds) are swinging most strongly from the Conservatives to Labour (9.5 per cent swing), compared to both younger people (4.5 per cent) and older (2.5 per cent). The good news for Cameron is that he is not losing his core vote of ‘grey voters’ to the new Labour leader; the bad news is that his success in appealing to middle-aged Britain and young people was short-lived.

While Brown does appear to be amalgamating support from a range of groups, in many cases the support is at best tenuous. Men and middle-aged Britain generally are giving Brown the benefit of the doubt in comparison to Cameron – but if Brown is not seen to perform well, or is seen to fall back to Blair’s tactics and policies, this support will flow rapidly back to Cameron.

In addition, Brown’s consolidation of fringe Lib Dem support (mainly among women and young people) will depend on his current stance on Iraq and his recent focus on public services. If in the coming months he is forced to make unpopular decisions on Iraq or the NHS, this support could surge back to the Lib Dems.

As Brown’s bounce trajectory draws him slowly back down towards earth, it will be essential for him to capitalise on the support he has garnered, and solidify it into a new ‘core’ of supporters for the Labour party.