The shy voter has reappeared — though this time as a Labour supporter. This “spiral of silence” is when some supporters of unpopular parties are reluctant or shy about expressing their voting preferences.

No one disputes that the Tories are doing well, and Labour very badly, at present. The question is how well or badly? Taking all published polls, Populus has broken down the record since the May 2005 election into six phases:

1. Until David Cameron became Tory leader in December 2005. Labour averaged 38.9 per cent, against 31.8 per cent for the Tories, and 21.1 per cent for the Lib Dems.

2. The Cameron honeymoon and Lib Dem turmoil over Charles Kennedy, until April 2006. Tories and Labour were virtually level on 36.5 per cent, with the Lib Dems on 18.7 per cent.

3. Tony Blair's end, from “triple whammy” of disasters in April 2006 until June 2007: Tories in a clear lead on 37.3 per cent, against 32.3per cent for Labour and 18.4 per cent for Lib Dems.

4. Gordon Brown honeymoon, June to October 2007: Labour on 38.9 per cent, Tories on 34 per cent and Lib Dems on 16 per cent.

5. Long winter, from cancellation of election until March 2008 Budget: Tories on 39.9 per cent, Labour on 34.2 per cent, and the Lib Dems on 15.7 per cent.

6. Since Budget: Tories up to 41.6per cent, Labour down to 29.1per cent, but Lib Dems gaining to 18.5 per cent.

This shows several key moments of change with the Budget and the 10p tax row, plus worries over fuel and food prices, triggering a collapse of confidence in Mr Brown and Labour. But the Lib Dems have benefited more than the Tories.

However, there has been an increased divergence of polling figures. YouGov, using internet polls, has put the Tories on 45 per cent, and Labour on 26.2 per cent, since late March. Over the same period, Populus and ICM, using telephone interviews, have put the Tories on just over 40 per cent, and Labour on 30.6 per cent. This translates into sharply contrasting Tory leads of 18.8 for YouGov and 9.5 points for Populus and ICM.

The obvious explanation is the re-emergence of the “spiral of silence”. YouGov argues that the shy voter phenomenon is the result of talking to an interviewer on a phone poll and does not arise with self-completion internet surveys. So YouGov does not adjust. However, Populus believes that there is an increasing “spiral of silence” among Labour voters. This is suggested by a marked growth over the past two or three months in the proportion of people who voted Labour at the last election and now saying they do not know how they would vote in an election tomorrow.

Hence Populus adjusts for those disclosing their past intention but refusing to disclose their current preference or saying they don't know (see www.populus.co.uk). This knocked three points off the Tory lead this month. The spiral of silence adjustment was seven points in Crewe & Nantwich according to ICM, though in this case shy voters may abstain. None of this, I repeat, alters the fact that Labour is now in dreadful trouble, and the Tories are well ahead. The question is by how much.

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