Who's going to win in St Albans? Anne vs Sandy

I normally have a good feel for election results but I'm finding the result in St Albans very hard to predict. It is clear to me that this is a straight fight between the Lib Dems and Conservatives- Labour have dropped completely out of the picture locally since 2005 and it seems like they are barely running a campaign in St Albans this time. In the 2009 local elections the results for the constituency area were: Liberal Democrats 43%, Conservatives 33%, Green 11.8%, Labour 11.1%. I think the key questions for predicting the result are:

1. How many people who voted Liberal Democrat in the local elections vote Conservative in the general election?

2. Will natural Labour supporters who voted Liberal Democrat in the local elections continue to support them in the general election or will they return to Labour?

Does anyone have any thoughts? Are you somebody who votes Liberal in local elections but Labour or Conservative in general elections?