UPDATED Sunday 8am

Is Tony Blair really heading for a 174 seat majority?

Today’s Independent on Sunday survey, conducted by Communicate Research, puts Labour at a level that is higher than it achieved in the 2001 landslide and gives the party a lead of 12% over the Conservatives that would on the Martin Baxter calculation produce a majority of 174.

With just five weeks to go before a May 5 election these are sensational figures but somewhat surprisingly the IoS story merits just three paragraphs and makes no reference to the 2001 General Election comparisons.

The March figures are with comparisons on last month – LAB 43 (+2): CON 31 (-3): LD 17 (n/c) – so both the Lib Dem and the Tories are down on their 2001 performance. The survey took place before the Howard Flight sacking and was carried out at the same time as the March YouGov poll which had just a 1% Labour lead. Clearly both pollsters cannot be right.

Polling experts observe that CR do not prompt for party choice – which usually gives bigger Lib Dem figures – and does not weight its results according to what interviewees say they voted last time. The latter is a measure used by the other telephone pollsters – ICM, NOP and Populus – to ensure that their samples are not skewed and this can have a huge impact. Without it the March NOP poll would have shown a Labour lead of 13% not the 5% that was reported.

If Communicate Research had included only those certain to vote, their figures would have been LAB 41%: CON 34%: LD 15%. As well as the YouGov poll the Communicate survey is in marked contrast to three other polls in the past five days.

CR’s Labour lead is 4% greater than ICM which does use past vote weighting and presents the party options to those being interviewed
CR’s Labour lead is 12% greater than the March Mori poll which had the two main parties level-pegging
CR’s Labour lead is 14.8% greater than the 2.8% Tory lead that the massive British Election Study reported amongst those “certain to vote” earlier in the week.

We do not expect that the poll will have a big impact on the betting markets which have seen very little movement throughout the day in spite of the Howard Flight sacking row.

Mike Smithson