Political turning points are normally only obvious in retrospect. That is what makes the latest batch of polls so intriguing: could we be at the start of a potentially decisive, and lasting, shift in the polls against Labour, similar to the 1992-93 swing against the Tories?.

The rise in Conservative support to above 40 per cent is not the key change, music though it is to the ears of David Cameron in the face of complaints in the Tory blogosphere about “why aren’t the Tories doing better?” The Conservatives have already been above 40 per cent on nine previous occasions this year.

Moreover, as Professor John Curtice, of Strathcylde University, has noted: “Every postwar opposition that won the next election secured 50 per cent in the polls at some point. Mr Cameron is a long way from that target.” Still, if sustained, this trend potentially gives the Tories a commanding position.

The more significant shift is the sharp fall in Labour support, from an average of 34 per cent in five polls before the Budget to an average of less than 30 per cent in three polls since then. This is the first time this year that Labour support has dropped below this level, and it only occurred four times last year. This is very dangerous territory for Labour, akin to the trough into which the Conservatives plunged in the mid-1990s.

The main recent event has, of course, been the Budget. The puzzle is that, as both the Populus poll in The Times and other polls have shown, individual tax measures — on cars, drink duties etc — have had a generally positive reception. But a majority believe that their taxes will rise and that they will be worse off. And voters are very sceptical about how well their higher taxes are being spent. Overall, they are negative about Alistair Darling and the Government’s handling of the economy.

Anthony Wells, of UK Polling Report, suggests that “it is possible that people support what Mr Darling has done given the circumstances he faces, but the fact that the Government has found itself in such circumstances has undermined their previous confidence in Brown’s handling of the economy”. Professor Curtice adds: “Mr Darling’s problem may be an inability to lift morale.”

For most British voters — except those in financial services — an economic downturn is still a threat on the horizon, not a current fact. Unemployment has fallen again and the travel industry reports no fall-off in bookings yet. Of course, fuel bills have risen sharply and new housing activity is down, but there has been no wave of repossessions so far. The increased pessimism is more a response to bad headlines about financial turbulence and fears of what may come.

Labour is also suffering from the absence of any clear-cut recovery strategy. Last week Mr Darling offered the “crossed-fingers” hope that the slowdown would not be too severe. But there is little sense from the Government of how in, the long term, public finances will restored to health or, for instance, the child poverty targets will be hit. Gordon Brown’s offer in The Sun yesterday of “a guarantee” that we will hold on to stability in tough times means little in practice. The Government needs a harder edge; as Hazel Blears said last night: “If we retreat into our comfort zone, and duck the tough issues such as crime and immigration, our coalition will fracture.”

Senior ministers fear that Labour faces a very rough 12 to 18 months, making a full-term 2010 election increasingly likely. Voters are in a gloomy, fatalistic mood, which is never good news for a governing party.

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