One of the many tricks that the LibDems use in by-elections is to lay plenty of money on their candidate in the hope of forcing down the odds and making it look like they have momentum in the campaign. They can then say to people that even the bookies agree that only the LibDems can beat X, where X is any party you care to name.
Today William Hill opened the betting on the bitterly fought Ealing Southall by-election with Labour as favourites and Conservative Tony Lit as second favourite. The LibDems are a poor third - meaning, by LibDem logic, that only Tony Lit can beat Labour! Is this as a result of genuine Tory momentum in the campaign? I've no idea, but I'm sure there'll be a few more seething LibDems out there - one told me a week or so ago that this was theirs to win. It seems that Lit and Cameron (plus the electorate) think otherwise.