There’s a new poll out this afternoon from YouGov which was commissioned by Channel 4 news and which suggests that David Cameron is heading for a three-figure majority.

The poll has been done on a format that I have never seen before – those questioned were limited to 60 key constituencies where Labour is defending majorities of between 6 per cent and 14 per cent. So it’s unlike the standard marginal polls that we have seen in the past where the two parties are much closer.

YouGov’s Peter Kellner writes on the C4 website: “..But if the Tories make inroads into our Battleground Britain seats, then they will be the largest party; and if they scoop the lot, they will have an overall majority (and unseat, among others, Ruth Kelly, the transport secretary, and Tony McNulty, the home office minister).

That would need a swing of 7 per cent. Our poll indicates that the current swing is 12 per cent. Such a swing would give the Tories a majority of around 150 if the election were held this week. One casualty could be Jack Straw, the justice secretary.

Could these seats behave differently, if and when voters realise they live in a key marginal? We asked people later in our survey how they would vote “if you were convinced that the only two parties with a realistic chance of winning in your constituency were Labour or the Conservatives?” Some voters switch from Lib Dem and minor parties, with Labour picking up more than the Conservatives. But the pro-Tory swing is still a sizeable 10.5 per cent, enough to give David Cameron a majority of 110.”

The notion behind this poll makes a lot of sense in the current political climate. Standard polls of marginals don’t add to our understanding at all.

There’ll be a full report on the survey on C4 News at 7pm.

Mike Smithson