Shipley, West Yorkshire: In these dank lands of balsam, hawthorn and graffiti tags, we rarely meet anything out of the ordinary

On the sunlit chalk downlands of southern England, a flitting bright-blue butterfly poses an identification puzzle. Could it be an adonis blue? A chalkhill blue? A common blue?

I am not on the sunlit chalk downlands of southern England. I am among brambles, in a sloping reach of untended land that separates the train station from the waters of Bradford Beck, at one time the most polluted river in England. This butterfly – jinking low across the tops of the brambles and brackens – can only be a common blue. There’s something to be said for narrow horizons, a trammelled perspective.