On the surface, the lastest monthly Ipsos MORI poll  contains good news for Labour. While ICM had them level-pegging with the Tories on 36%, MORI puts them 11 points ahead, up seven points since June and the kind of lead the opposition needs to justify hope that it can win the next election.
But dig deeper, and more worrying findings emerge. While David Cameron's net satisfaction rating has risen by eight points since last month to -16, the highest level this year, Miliband's has fallen by five points to -26, the lowest level since January 2012. As the graphic below shows, the Labour leader's rating is now as low as William Hague's was at this stage of his leadership. While Cameron outpolls his party by nine points (38-29), Miliband trails his by 10.
But this is a parliamentary system, you say, why should we care? The answer is that personal ratings are frequently a better long-term indicator of the election result than voting intentions. Labour often led the Tories under Neil Kinnock, for instance (sometimes by as much as 24 points), but Kinnock was never rated above John Major as a potential prime minister. A more recent example is the 2011 Scottish parliament election, which saw Alex Salmond ranked above Iain Gray even as Labour led in the polls. The final result, of course, was an SNP majority.
There are some notable exceptions to this rule. Margaret Thatcher won in 1979 despite trailing  Jim Callaghan by 19 points as the "best prime minister" and Ted Heath defeated the more popular  Harold Wilson in 1970. But Labour should not assume that history will repeat itself in their favour. Miliband's substandard ratings mean the Tories are confident that if they frame the next election as a presidential contest, they stand a good chance of remaining the largest party.