In my experience, few people follow political opinion polls as closely as politicians and their advisers – even if they are often the first to dismiss or downplay them. That is because polls do more than measure public opinion. They help set the political narrative and influence how parties and their leaders position themselves. Just as the CEO of a listed company is held accountable with quarterly earnings announcements, so too are political leaders increasingly judged by the regular verdict delivered by opinion polls.  They may question the methodology, dismiss the findings or point to the limitations of a particular…