It takes more votes to elect a Conservative than a Labour MP, owing to the over-representation of urban Britain and some majority-Labour parts of the country. As a result, psephologists calculate that the Conservatives have to win at least 4% more of the popular vote than Labour in order to win more seats.
一些因素让预测结果变得难上加难。首先，选举制度的设计极有利于工党。保守党成为议员所需要比工党赢得更多选票，因为城市英国居民拥有过多的代表权，而工党在不少英国选区占据多数优势。结果，选举专家测算，保守党必须至少赢得比工党高4%的支持才能拿下更多席位。