Something was missing. His preliminary sketch of the Sankey Viaduct was both dramatic and satisfyingly precise, but it needed something to anchor it, a human dimension to give a sense of scale. He knew exactly where to place the figures, and he could easily have pencilled them in, but he preferred to rely on chance rather than imagination. Ambrose Hooper had been an artist for over forty years and his continued success could not simply be attributed to his sharp eye and gifted hand. In all that he did, luck played a decisive part. It was uncanny. Whenever he needed to add a crucial element to a painting, he did not have to wait long for inspiration to come. An idea somehow presented itself before him.

Hooper was a short, slim, angular man in his sixties with a full beard and long grey hair that fell like a waterfall from beneath his battered old straw hat. On a hot summer's day, he had taken off his crumpled white jacket so that he could work at his easel in his shirtsleeves. He wore tiny spectacles and narrowed his lids to peer through them. An experienced landscape artist, it was the first time that he had turned his attention to the massive railway system that had changed the face of the English countryside so radically over the previous twenty years. It was a challenge for him.

Viewed from below, the Sankey Viaduct was truly imposing. It had been opened in 1830 as part of the Liverpool and Manchester Railway and was roughly halfway between the two places. Straddling a valley that contained both a canal and a brook, the viaduct was supported by nine identical arches, each with a span of fifty feet. Massive piers rose up with perpendicular certitude from the piles that had been driven deep down into the waterbeds, and the parapet coping reached a height of almost seventy feet, leaving ample room to spare for the tallest vessels that sailed on the canal. It was a predominantly brick structure, finished off with dressings and facings that gave it an added lustre. In the bright sunshine, it was a dazzling piece of architectural masonry.