The British public wants a referendum on Europe, but has rewarded, rather than punished, the parties which last week denied one to them. That is one reading of the latest Populus poll for The Times, undertaken over the weekend, which puts Labour up three points on a month ago at 34 per cent, the Liberal Democrats up two points at 19 per cent, but the Conservatives down three points at 37 per cent.

A more plausible interpretation is that it is like the Western Front in the First World War with small frontline changes in a long battle of attrition. Once you take account of rounding and the margin of error, month-to-month shifts appear less significant. The Tories are ahead, as they have been in most polls since spring 2006 but their position is not as commanding as Labour’s in the 1994-97 period. The Tory lead has narrowed slightly since mid-February as Labour has moved to the top end of its range.

The Lib Dem rating has fluctuated in the upper teens. Their latest gain can be attributed to being in the news over their split about an EU referendum last week. This has not, however, done Nick Clegg personally any good. His leader rating (on a 0 to 10 scale) has fallen since January from 4.4 to 4.16, the lowest so far for a Lib Dem leader, while his rating among Lib Dem voters has fallen sharply from 6.5 to 5.63, which by chance is exactly the same as Sir Menzies Campbell’s final rating among his own supporters last July. However, the poll was largely undertaken before Mr Clegg’s leader speech at his party’s spring conference.

Labour appears to have bottomed out, but still cannot be said to be recovering. Mr Brown’s leader rating is virtually the same as in January at 4.59, and at 6.72 among Labour voters.

The poll has some consolation for David Cameron. His personal rating has risen from 5.07 to 5.23 since January and is, by a wide margin, the highest of the three party leaders, though slightly below his peak in early 2006.

The poll underlines the complexities of the EU issue. Voters are evenly divided, 37 to 37 per cent, on whether the treaty is largely the same as the old EU constitution and would transfer significant further powers to the EU, or whether it mainly consists of technical and procedural changes and would not transfer such powers. But 26 per cent are don’t knows.

The vast majority of voters (70 per cent) favour some sort of referendum on Europe, with just 19 per cent disagreeing. But there are big variations in preferences: 18 per cent want one just on the Lisbon treaty; 16 per cent one on whether Britain should stay in the EU, but not on the treaty; and 36 per cent a referendum on both in and out of the EU and on the treaty. Just 19 per cent do not believe there is a need for any referendum on the EU.

Populus interviewed a random sample of 1,502 adults aged over 18 by telephone between March 7 and 9. Interviews were conducted across the country and the results have been weighted to be representative of all adults. Populus is a member of the British Polling council.

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