The Destruction of Pompeii and Herculaneum is a large 1822 painting by English artist John Martin of the eruption of Mount Vesuvius in 79 AD.
It follows the pattern set by his previous successful painting, Belshazzar's Feast, which was another depiction of a dramatic scene from history delivered from an esoteric point of view.
Martin was (unusually) commissioned to paint the subject by Richard Greville, 1st Duke of Buckingham and Chandos, who paid 800 guineas.
Johnstone found the damaged work rolled up inside the canvas of Paul Delaroche's painting The Execution of Lady Jane Grey, which had also been forgotten and lost.
Maisey replaced the missing section, by drawing on photographs, Martin's smaller painting of the same subject from Tabley House, and an outline etching of the original.