WALK into the National Gallery in the coming year and just around the corner from the Monarch of the Glen (in case you get lost), is a new two room display of undisputed masterpieces and associated works. On tour from London, Constable’s Salisbury Cathedral from the Meadows, dubbed “the Great Salisbury” by the painter himself , who considered it one of his best works, has been mounted, rather like some epic impressionistic diptych, with the National Gallery’s own bravura McTaggart, The Storm.

They have been brought together as part of a tour of the Constable from the Tate around five partner galleries in the UK, which will see the painting coupled with a new work in each of the institutions.

On the face of it, the Constable and the McTaggart are two very different paintings. Constable’s is a rural landscape; McTaggart’s a wild seascape. But the similarities and meeting points are acute, whether in the interest in the stormy weather (although Constable’s, with its high-arcing rainbow over the Cathedral, is more suggestive of an end to the storm than McTaggart’s boiling, whitewashed seas), the free brush strokes, the human detail in the vast canvas of Nature. Even the size is a close-fit; Salisbury is one of Constable’s vast and influential “six-footers” and the McTaggart matches it nearly to the inch. This was Nature writ large and deliberately so, Constable wading against an established tide, at the Royal Academy, of Classicism and History paintings.

Constable’s Salisbury Cathedral, with its dynamic, dark cloudscape, was painted at a key moment in the painter’s life. His wife, Maria Bicknell, had died of tuberculosis in 1828. Grief-stricken, Constable (1776-1837) wrote to his brother, “The face of the world is totally changed to me.” He started work on the painting the year after, the work being understood in most circles as a memorial, sketched in the open air at a place which had had so much meaning to the couple. It was also the home of his great friend, the Reverend John Fisher, son of the Bishop of Salisbury.

Fisher, who lived in the house at the end of Constable’s Salisbury rainbow, admiringly dubbed the work “The Church under a cloud.” It was a pointed comment, both aptly descriptive of Constable’s own fruitful preoccupation with Nature, and of the underlying politics of the time – for the Church itself was indeed under a cloud, a reforming and political cloud with which Constable, a devout Anglican, was most concerned.

And what a cloud. An electrical storm of some magnificence, the white light is flecked across the surface of the canvas in quintessential Constable style, known as “Constable’s snow”. It’s juxtaposition of loose and detailed brushwork was not to the taste of some contemporaries, nonetheless, who criticised him for “lack of finish”.

There is the curious matter, too, of the rainbow, which was added at some point after the RA exhibition – it has recently been suggested as a memorial to his friend, Fisher, who died some few years after Maria. And yet you might say Constable was an inveterate “fiddler”, an artist who never quite considered a painting complete, frequently asking for loans of his works back from buyers so that he could make alterations. The oil sketches that accompany this show, including one from the Salisbury series, show this evolving approach to composition and finish.

Constable’s fluidity and impressionistic brushstrokes which attempted serious innovation in the reproduction of the effects of Nature, made a great impression on the young McTaggart (1835-1910) whose own impressionistic but detailed brushwork would make him one of Scotland’s most renowned 19th century painters.

“The more I’ve looked at it, the more I’ve seen links between the two paintings we have on display here,” says Charlotte Topsfield, senior curator at the National Galleries. The Storm, which in size and ambition is almost exactly matched to Constable’s “Great Salisbury”, is a bravura frenzy of palette knife, brushwork and oil, depicting the inhabitants of a fishing village – which looks as if it might, at any moment, be consumed by the white wash of storm in the sea at its shores – attempting to rescue a fishing boat that is in trouble just offshore.

“There is a direct connection – we know McTaggart was interested in and inspired by Constable. And we know, too, from McTaggart’s biographer, that he took every opportunity to see Constable’s work.”

In the 1880s, Constable’s oil sketches, which had been kept in his family rather than sold, were displayed in Edinburgh.

“We think that McTaggart studied them,” says Topsfield, who tells me it coincided with a transitional point in McTaggart’s work when he started painting outdoors and using more impressionistic brushwork, which has more in common with Constable than the Impressionists he would also have seen in London. “The Storm is still about the link between man and the elements, something which was very much what Constable was concerned with.”

Fleshing out the story, more oil sketches and prints from Constable and McTaggart, which show in some small way the trajectories of two painters of successive generations whose concerns and ideals were in many ways closely allied.

Constable and McTaggart: A Meeting of Two Masterpieces, National Gallery of Scotland, Edinburgh until March 25, 2018

www.nationalgalleries.org