Has any painting had such a disruptive effect upon an artist’s reputation as John Constable’s The Hay Wain? When it was first shown at London’s Royal Academy, in 1821, it failed to find a buyer. Subsequently shown in Paris, in 1824, it excited the so-called Barbizon school of artists. Their passion for realistic depictions of rural life, painted en plein air, inspired Impressionists such as Monet and Post-Impressionists like Van Gogh.

In its compassionate yet unsentimental depiction of rural life, The Hay Wain was radical and innovative — arguably the starting point of modern art. Yet today it is often dismissed as chocolate-box. There are two reasons for this injustice. One reason is its sheer ubiquity. The most popular English landscape painting, reproduced on countless knick-knacks, it has vanished into the foreground, robbed of its original power.

The other reason is more insidious. The Hay Wain, and other Constable landscapes of the same ilk, evoke a discreet and modest patriotism, a feeling of kinship with the English countryside and its people — a shared sense of belonging that transcends conventional politics. In today’s art world, such patriotic sentiments are unfashionable, to say the least.

Constable evokes these tender feelings because of his deep understanding of the English countryside — above all the countryside around East Bergholt, on the River Stour (which forms the border between Essex and Suffolk) where he was born and raised. He depicted its topography so profoundly that, even within his own lifetime, it became known as Constable Country.

There’s nothing dramatic about Constable Country. The Stour runs through pretty flood plains, but the terrain is unremarkable. Then as now, the surrounding fields are rigorously farmed. Constable’s father was a wealthy miller who ran a fleet of barges along this busy waterway. This was no romantic wilderness, but an industrious, workaday place.

Yet it’s the very ordinariness of this scenery that inspires such fierce affection. Most of us can recall a place like this from our childhoods, a little village in the green belt with a river running through it, with woods and meadows beyond where we used to play. The remorseless encroachment of suburbia makes these precious memories even more acute.

“The stillness of noon, the depths of twilight and the dews and pearls of morning are all to be found on the canvases of this most benevolent and kindly man,” declared Constable. “On looking at them one finds tears in one’s eyes and knows not what brings them.” He was talking about his hero, Gainsborough, but he might have been talking about himself.

Constable — The Dark Side is a small show in a small gallery, but it makes an important contribution to the current reassessment of Constable’s artistic merits. In a deft selection of pictures, all contained within a single room, curator Nicola Moorby reminds us that he was a daring and often disquieting artist, rather than a painter of whimsical, bucolic scenes.

Open your eyes, take a closer look and you’ll realise you were mistaken

If you shut your eyes and imagine a Constable painting, you’ll probably picture lush green fields beneath a clear blue sky. Open your eyes, take a closer look and you’ll realise you were mistaken. Our idea of him has become distorted. This compact show will change your mind.

These pictures are loaned from four major museums: the Royal Academy, the Tate, the V&A and Gainsborough’s House in Sudbury (barely 20 miles from East Bergholt, along the River Stour). Even if you’re a frequent visitor to those galleries, you’ll be sure to find some unfamiliar artworks here. There’s only one “six-footer” — the term Constable used for his full-sized paintings, executed for public display. Most are smaller sketches, intended for his eyes only, which reveal his love of stormy skies.

Constable knew the English countryside far too well to prettify it. His wasn’t the shallow infatuation of the sightseer, but the enduring empathy of the lifelong countryman. It was a marriage, not a fling. His landscape paintings are so poignant because the sunlight is so fleeting. Even his Hay Wain is beset by darkening clouds and the threat of rain and thunder.

There’s no Hay Wain here, no Flatford Mill, none of his greatest hits — but those pictures have been worn smooth by familiarity. This exhibition forces you to look at Constable with fresh eyes. The picture that encapsulates its ethos is Rainstorm over the Sea, painted in Brighton in 1824. This trip to the seaside was for the benefit of his wife Maria, in the forlorn hope that the sea air might bring her some brief respite from the tuberculosis that would finally kill her, only four years later, at the age of just 41.

Constable didn’t care for Brighton — he called it “Piccadilly by the seaside” — but even the tawdry dazzle of this brash resort couldn’t sully the elemental beauty of a rainstorm out at sea. Constable captures the drama of the scene with magnificent bravura. His brushstrokes are so wild and the overall effect so abstract that I initially assumed it must be a late Turner.

My mistake was instructive, for whilst Turner is lionised as a groundbreaking, progressive artist, Constable’s subtler achievements are often overlooked. It was ever thus: Turner became a Royal Academician in his twenties, Constable had to wait until his fifties; Constable was the tortoise, Turner was the hare. Yet after several centuries as the Gainsborough to Turner’s Reynolds, the balance of the race may be about to shift in Constable’s favour. Turner’s flamboyance suited the easy certainties of the 20th century. Constable’s sensitivity is more attuned to the troubles of our own age. As Constable said himself, “Fashion will have its day — only truth will last.”

Constable — The Dark Side is at The Arc, Winchester (www.arcwinchester.org.uk) until 16th August.