I know little about the science or the research but this extended article from (an unlikely source) The Observer has convinced me of the need for a cull. It seems clear that the badger - an animal with no natural predator - is linked to the spread of bovine TB, and that an entire British industry stands in jeopardy because of our inaction.
Incidentally, the piece convinced me of two additional things - (1) that that ministers in this government desperately punt issues off for "further study" rather than ever make a hard decision (ok, I was convinced of that already) and (2) that if Kenneth Grahame hadn't written Wind in the Willows, far fewer people would care about this issue.