Lord Ashcroft's giant poll of 8,000 voters for ConservativeHome contains much that is worrying for Labour and Ed Miliband. More than half of those surveyed (52 per cent) say "Labour have not yet learned the right lessons from what went wrong during their time in government, and cannot yet be trusted to run the country again". In addition, even after a double-dip recession, David Cameron and George Osborne are still more trusted to manage the economy than Miliband and Ed Balls (by 53 per cent to 47 per cent), and Cameron has a 12-point lead over Miliband as the best prime minister (56 per cent to 44 per cent).

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.

However, it's still worth highlighting one finding which should give Labour heart. Asked which party they would like to see in power in 2015 (see table below), rather than merely which they would vote for in an election tomorrow (a subtle but important distinction), 56 per cent say they would like to see a Labour-led government (36 per cent favour a Labour government and 20 per cent a Labour-Lib Dem coalition), while only 44 per cent say they would like to see a Conservative-led government, with 31 per cent favouring a Conservative government and 13 per cent a Conservative-Lib Dem coalition.

Ninety three per cent of Labour joiners - those who did not vote for the party at the last election but say they would do so tomorrow - would like to see the party in power in some form after the next election. Even among Labour considerers, those who did not vote Labour in 2010 and would not do so in an election tomorrow, but say they would consider the party in the future, the figure is 72 per cent.

This is significant because it suggests that voters increasingly view Labour as an alternative government, rather than merely a receptacle for protest votes. For those Tories who console themselves with the thought that voters will drift back them before 2015 (and that new ones will join them), it is a worrying development.