Which seems a melancholy verdict on what has looked for a decade like the closest thing yet seen to a mass lottery win.经济学人杂志上看到的，揣摩了半天也没看出来主谓宾，请指教。

which 相当于是引导一个非限定定语从句，指代前面的一段话his party will accept a bonfire of planning restrictions when it is convinced that there is a good, economically liberal case for it，由于被中间一段话隔开，干脆另开一句作为强调。

作为从句，which主语，seems谓语，a melancholy verdict表语，on what has looked for a decade 介词+宾语从句，修饰 verdict。介词like短语作状语。

翻译：这好像是期盼了许多年却只得到一个令人沮丧的判决，就跟中彩票一样希望渺茫。