A blip or a turning point? A fuel protest of 2000, or a Black Wednesday of 1992? Gordon Brown is suffering sharper media and parliamentary criticism than he has ever faced.

For all the recent stark headlines, the polling message is mixed. A new Populus poll for The Times, undertaken between Friday evening and Sunday, puts Labour on 40 per cent, up one point since the last poll between Tuesday and Thursday. The Tories are on 38 per cent, up two points, and the Liberal Democrats are three points down at a new low for Populus of 12 per cent.

More than four fifths of the interviews (815 out of 1,008) were undertaken before the announcement on Saturday afternoon that there would be no election this year. So it is impossible to assess any post-announcement impact. (For fuller details, see www.populus.co.uk)

There are two striking points about the poll. First, Labour support has, with only a couple of exceptions, been remarkably stable at about 39 to 40 per cent, plus or minus a point or two, that is within the margin of error. Parties other than the big three have also been stable at about 10 per cent.

Secondly, most of the movement in the past fortnight has been between the Tories and the Liberal Democrats. For instance, the Tories’ average rating in all published polls has risen from 33 per cent in September to 38 per cent so far this month, while Liberal Democrat support has fallen from 16 to 13 per cent.

Such a sharp fluctuation may reflect the unstable conditions of the conference season, rather than any underlying shift. Have nearly a quarter of former Lib Dem supporters defected to the Tories after their promises about inheritance tax?

The relationship to watch will be between Labour and the Tories. Only if, and when, the Tories start overtaking Labour will it be possible to talk about a turning point. That is what happened in the other direction in two stages: in the autumn of 1992, after Black Wednesday, and in the spring of 1993, after the Major Government’s tax-raising proposals. The Tories never recovered. It is premature to believe that this has yet occurred. Labour is still ahead, just, or level-pegging in all but two national polls. The Tory lead could be as short-lived now as it was in September 2000 during the fuel protests.

Nevertheless, the latest Populus poll has some warnings for Mr Brown. Even in the middle of the Northern Rock panic, 56 per cent of voters still trusted the Brown-Alistair Darling team to deal with any problems facing the British economy in the months or years ahead, while just 18 per cent trusted the David Cameron-George Osborne team. Now the gap has narrowed substantially to 43 per cent backing for Mr Brown and Mr Darling, while trust in Mr Cameron and Mr Osborne has risen by 10 points to 28 per cent. Labour still has the edge on economic management, but could be vulnerable with conditions expected to become tighter next year.

The Tories should not get too euphoric. Mr Brown’s blunders have negated the gains that Labour achieved in the summer, and have boosted the Tories, while opening up the tax issue.

Mr Cameron looks more credibile and Mr Brown fallible but, so far, this is only an opportunity, not a turning point.

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