As museums around the world celebrate the 250th birthday of JMW Turner, it's time to reappraise his beloved and celebrated painting, The Fighting Temeraire.

JMW Turner's The Fighting Temeraire became a national celebrity when it was first unveiled in 1839, and its fame has endured to the present day. It was once voted Britain's favourite painting and currently features on £20 banknotes. But the widely accepted interpretation of this iconic painting's message might, in fact, contradict Turner's true intentions.

The "Temeraire" of the title refers to a 98-gun warship of the British Navy, which is depicted in the painting's background. It was a hero in Britain's defence against France during the Napoleonic Wars, but it caught the nation's attention in 1838 when it was dismantled and its parts sold off. Turner's painting depicts this once-mighty gladiator of the seas being towed down a burnished River Thames by a much more recently invented steam-powered tugboat.

A brief segment in the 2012 James Bond film Skyfall captures a popular view about the painting. In the scene, Bond (Daniel Craig) meets Q (Ben Whishaw), his new head of research and development, in London's National Gallery, and they sit in front of The Fighting Temeraire. "It always makes me feel a little melancholy", says the young, tech-savvy Q, in a pointed jibe to 007, an old-school field agent. "A grand old warship being ignominiously hauled away for scrap."

This echoes the widely held belief that the painting evokes a sense of nostalgia and faded national glory. According to this view, the ghostly Temeraire is the painting's heroine, and the tugboat its villain. In the 19th Century, the English writer William Makepeace Thackeray referred to the smaller vessel as "a little, spiteful, diabolical steamer" and the American novelist Herman Melville called it "a pygmy steam-tug" by comparison to the "Titan Temeraire".

You can see why Turner's original audience may have sympathised with the humbled HMS Temeraire and been saddened by her fate. Back in 1804, she had played a critical role in blockading French ports and defending the British coast. But her finest moment came on the afternoon of 21 October 1805, in the Atlantic Ocean, just off the coast of south-west Spain.

At this pivotal hour, the Battle of Trafalgar, a deadly sea battle between the British Royal Navy and the combined fleets of Spain and France, was at its climax. Admiral Lord Nelson's flagship HMS Victory had led the attack but was being pummelled by the French vessel Redoubtable. Then, out of the cannon smoke, surged HMS Temeraire, followed by a war-hungry flotilla of British vessels. The Temeraire blasted the Redoubtable with her guns and endured a hailstorm of cannon volleys in return – an onslaught that lacerated the ship and spattered her decks with blood. But like a stalwart prize-fighter, the Temeraire weathered the bout. She valiantly protected her flagship and played a vital part in the British navy's ultimate victory in the Battle of Trafalgar.

Turner was 64 when he painted The Fighting Temeraire. He was born in 1775 in a down-at-heel area of London near Covent Garden but managed to enrol at the prestigious Royal Academy of Arts aged 14. He became an Academician at the precocious age of 24, and a Professor of Perspective when he was just........

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