If Ed Ball's is to be believed, and the Labour source that said that "Thursday will be better" than Tuesday then there is another defection in the offing for Gordon Brown tomorrow, and it's going to bigger than Quentin Davies. That suggests someone fairly major, the question is who? After the Davies defection you'd think that to be better it would have to be someone who was slightly more inclined towards Labour sensibilities. After all, Davies is not exactly a shining example of left wing thinking. So whoever it is will be someone who has expressed views that lean leftward.
Of course, it's likely that they would be someone not always on the Left, and have probably moved slowly leftwards over time. Possibly influenced by someone in their personal relationships, who may or may not be known to symapthise with the Labour Party. They'll probably have been a member of traditional right wing groups like No Turning Back or the Monday Club at some point. I imagine they've rebelled quite a lot against the Tory whip as well, under at least three leaders, and probably, although not necessarily, served in the Shadow Cabinet that Quentin Davies did. They may have even rebelled in recent weeks over something like the Grammar school row, and perhaps - if Balls is not telling porkies - past rebellions have been orchestrated by Labour defection handlers?
It's also likely that any defection would be "numbers neutral" in the sense that at a General Election they would stand no chance of ever retaining the seat they currently have (like Quentin Davies), and Brown could do with a friendly southern face for his new Cabinet, so the Home Counties would be a the place to look I guess. A defector would also, I'd say, probably be someone who has their current seat by virtue of having the word "Conservative" in front of their name on the ballot paper, rather than because they were, necessarily, an obvious Tory.
Given all these sort of requirements, the potential list - if Balls is to be believed - can't be very long, can it? Or maybe Balls is talking balls.