An exclusive Politics Home study of 35,000 voters in 238 marginal constituencies, based on fieldwork carried out by YouGov predicts that if an election were held now the Conservatives would win 398 seats, Labour 160, and the Lib/Dems 44. This is one of the largest surveys of marginal seats ever attempted. You can read a report summarising the results here, ) Marginal seats have been grouped into 17 categegories, and an overall swing based on the total votes in that category applied to Anthony Wells' estimate of the notional 2005 results. In terms of the overall national position the evidence provided by this survey is quite powerful, but in terms of individual seats, where the sample sizes were between 100 and 400, not too much weight should be given to it. For example, one of the categories consists of the four Labour-held seats in Cumbria, where 536 adults took part, of whom on a standard voting intention 39% intended to vote Conservative, 36% Labour, and 16% Lib/Dem. (They asked