OPULAR photographs of the Pontcysyllte Aqueduct show walkers blithely passing along its narrow towpath and canal boats inching along an 11ft-wide trough as their occupants airily gaze into the far distance, as if it was the most natural thing in the world to be 130ft up in the air with nothing more than a thin metal handrail on one side and a gaping void on the other between them and the River Dee far below. Not a venture to be undertaken on a gusty day or, for acrophobics, on any sort of day.
