Entirely self-taught, Gardner developed an exceptional command of draughtsmanship and composition, enabling him to depict ships and naval engagements with remarkable technical accuracy. His paintings are noted for their careful observation of structure, rigging and movement, alongside a nuanced handling of light and weather that conveys the changing conditions of the sea. Gardner’s lifelong connection to maritime life began early. His father served as Chief Engineer of the Clyde Trust and the Port of Glasgow, and exposure to docks, ships and industrial waterways shaped his interests from childhood. In 1934 he joined the Royal Naval Volunteer Reserve as a midshipman, and during the Second World War served aboard armed trawlers and destroyers in both the North Atlantic and the Mediterranean. These experiences gave him an intimate knowledge of naval vessels and life at sea, grounding his later work in lived experience rather than historical distance. He was mentioned in dispatches for distinguished service and left the Navy in 1948 with the rank of Commander.

Following the war, Gardner continued to work as a civil engineer overseas before returning to Britain and dedicating himself fully to painting. His reputation grew steadily through exhibitions in London and abroad, with collectors and institutions drawn to his ability to unite technical precision with historical narrative. In 1988 he was elected honorary vice-president for life by the Royal Society of Marine Artists, recognising his contribution to the field. A major highlight of his later career came in 2005, when an exhibition marking the bicentenary of the Battle of Trafalgar brought together a unique group of paintings depicting every ship in which Admiral Nelson had served. Today, Gardner’s work is represented in important public collections, including the National Maritime Museum, Greenwich, and remains a benchmark for British maritime painting.