To call Turner competitive is like saying Liberace could come across as a little camp. How competitive was he? So competitive that a new show at Tate Britain makes a point of revisiting what is widely hailed as the most famous episode of artistic rivalry in the history of British art.

The Tate is exhibiting Turner’s Helvoetsluys beside Constable’s The Opening of Waterloo Bridge. It’s the first time the two paintings have hung cheek by jowl since they were originally exhibited beside each other in the Royal Academy in 1832.

When Turner first saw his greyish swirling seascape contrasted against the the vibrant vermilions of Constable’s neighbouring canvas, he used the “varnishing” days preceeding the exhibition to embellish his seascape with a small red daub, in the shape of a buoy, so as to draw the viewer’s eye away from its neighbour and to make Constable’s reds look wan in comparison. “He has been here,” hissed Constable, “and fired a gun.”

By hanging Turner’s oils alongside those by artists who inspired him, and whom he rated as worthy rivals, the Tate’s new show confirms Turner as, in his own words, “the great lion of the day”, a painter whose genius would, in turn, inspire artists from Matisse (“What incandescences! What dazzle! What jewels!”) to Rothko (who joked: “That chap Turner learnt a lot from me”).

Yet what do we know of this driven, if unprepossessing, Cockney barber’s son from Covent Garden? He was a teenage prodigy; secretive, rich and unmarried. He owned a pub; had few friends. Many shared George V’s view that “Turner was mad . . . My grandmother [Queen Victoria] always said so.” Beyond that we know little. Luckily, his paintings talk eloquently enough for him.