Postcard showing shopfront of Mungle's General Store, West Calder.
In February 1871, David Lyon walked into Andrew Mungle's general store and asked for a light for his pipe. Some accounts suggest that Lyon was begging and making a nuisance of himself, and that shop staff starting to “chaff” him, throwing paraffin and threatening to set him alight (horrifying). Mungle's store, sited in the centre of West Calder, was licensed to hold up to 200 pounds of explosive as miners were expected to buy their own tools and explosive. The shop was lit by paraffin lamps and an open fire burned in a fireplace close to the counter.It seems that after about ten minutes of heated discussion, David Lyon grabbed a couple of bags of powder from the counter and threw them into the fire. There was a small explosion and then a much larger one which shattered doors and blew out shop windows into the street. William Prentice, one of two shop-men who had been weighing out the blasting powder, was standing close to fire and caught much of the blast. He ran into the street in a hysterical state with his clothes aflame and was eventually subdued by a crowd that had been drawn by the sound of the explosion, The scene of horror was witnessed by his sister Isabella. William's injuries proved fatal a week later.
David Lyon was charged with murder, which was reduced at trial to culpable homicide with a plea for leniency, He was sentenced to fifteen months imprisonment.