Would Labour do WORSE with Miliband?

The Times have published a hypothetical voting intention question from their latest Populus poll asking how people would vote if Gordon Brown was replaced by David Miliband. It gives voting intentions of CON 46%, LAB 26%, LDEM 16% - a Conservative lead of 20 points, compared to 16 in Populus's standard polls.

Does it mean anything? Probably not - it certainly doesn't predict what the short term effect of replacing Brown would be (remember how polls before Brown took over suggested he would produce a huge Tory lead, when in actual fact for a couple of months he enjoyed huge Labour leads), and I doubt very much most people have a good enough idea of who David Miliband is and what he would do as leader to make a accurate judgement on how they would react to it. In the case of Brown they'd had 10 years of him as chancellor to judge the man, with Miliband they've had only a year of so of him being foreign secretary.