At the northernmost remote point of Denmark, at the tip of a long spit of land where two seas meet, lies Skagen. Hans Christian Andersen described it in 1860 as a sparsely populated place, ‘a desert where the wind sports with the sand, and where the voices of the seamews and the wild swans strike harshly on the ear’.  Everything in this backwater was defined by fishing: outhouses had upturned boats for roofs, the daily catch was strung up on lines, and the water’s edge was strewn with surplus fish rejected by fishermen. ‘Dear, friendly, peaceful Skagen’, Andersen wrote. ‘They call it an out-of-the-way corner; but it’s a good warm chimney-corner, and its windows open towards every part of the world.’

Andersen was not the only artist to seek refuge in this isolated and somewhat desolate spot. By the early 1870s, painters from across Europe would start arriving in the town, drawn by its white sand dunes and perfect light. They frequented the Brøndum’s Hotel, where Andersen had also stayed, and eventually decorated the walls of the hotel with paintings of each other. The Brøndums had a daughter, Anna, who was artistically inclined herself and who married one of the visiting artists, Michael Ancher.

You may have seen Anna Ancher before. She and a friend are the two women in white who walk away from us along the seashore in a painting by Peder Severin Krøyer entitled Summer Evening on Skagen Beach, and she can also be seen toasting friends at a garden party in the same artist’s Hip, Hip, Hurrah! Both are frequently reproduced on posters and greeting cards. Now, Ancher herself is the subject of a major new exhibition at Dulwich Picture Gallery, Anna Ancher: Painting Light, her works complemented by evocative contemporary photographs of members of the Skagen artistic colony.

If it takes a village to raise a child, the same might be said of an artist. Ancher was strongly encouraged by her family and the artistic colony that had set up home in Skagen to train as a painter. Although she visited Copenhagen regularly and travelled with her husband to Berlin, Dresden, Vienna, Munich and Paris to see exhibitions, her focus as an artist was always on her local community. Thus, the Dulwich exhibition gives us an opportunity not only to appreciate Ancher as an artist, but to peer inside the lives of the ordinary people who lived in late 19th-century Skagen.

We meet seamstresses, family members plucking geese and chickens, an elderly woman counting out money, children being taught how to sew, an old man whittling sticks, a pastor giving an al fresco sermon to a hillside of sombre peasants, and even mothers and babies queuing up for a vaccination (a most unusual theme, but one Ancher painted repeatedly). Repeatedly, we meet Ancher’s mother, a rather stern-looking, devout Christian never seen without a head covering, who appears in a series of paintings that become increasingly focused on death.

Though these character studies, many of them in dark interiors and a little gauche in terms of facial detail, are interesting for what they tell us socially, they are not the most appealing works here. The exhibition is at its best when it shows Ancher in impressionistic mode. The most effective images on display – some of them quite bewitching – are those where light itself becomes the focal point of interest. In the gorgeous Sunlight in the Blue Room (1891), a shaft of light glances through a window and on to a wall, a carpet and a blond child’s hair. Though a charming, conventional image to our eyes, it provoked the ire of critics, who complained that the sitter’s yellow hair ‘is eaten up by the sun to the scalp’ and advised that artists should keep such misguided experiments behind closed doors.

But Ancher did not give up on her fascination with light and, by the early 1900s, had established a signature technique of capturing a luminescent brightness shining through white blinds and curtains or reflected onto a wall. A prime example is Lunch Before the Hunt (1903), in which a man eats his solitary repast in a room illuminated by a peachy golden haze that bounces off the chocolate fur of a hunting dog so velvety you want to reach in and give it a stroke.

Even more striking are the paintings where the play of light is the only subject of the work. Interior. Brøndum’s Annex (1916) depicts the view from one empty room into another, with bare floorboards, orange-toned woodwork and the honeyed reflection of windows onto a wall. In Evening Sun in the Artist’s Studio (after 1913), a similar effect is created with impasto technique: vibrant, rather abstract orange rectangles are daubed onto a bare blue-mauve wall to capture the effect of a sunset reflected from an unseen window. A tremendous sense of stillness and calm emanates from these images, which do so much with such economy of means. There are exterior scenes, too, which cast Skagen in a particular, seductive summer light, delicate blues morphing into shimmering pinks in the street scene Østerbyvej (c. 1915) and in Moorland (undated), in which three-quarters of the frame is devoted simply to sky.

‘Radical’ is a buzzword that contemporary curators, including the curator of this exhibition, tend to use rather too liberally in exhibition captions and catalogues. With its overtones of political activism, it seems too strong a word in this rather gentle context. (Ancher, indeed, referred to the suffrage debate as ‘the women’s nonsense’.) ‘Trailblazing’, however, would be a good alternative. Anna Ancher was a gifted artist who honed techniques ahead of their time and more daring than anything her own husband was doing. And she had an indomitable spirit.

Upon the birth of her daughter in 1883, her own painting tutor instructed her to gather up her art materials in a wheelbarrow and cast them out to sea. Ancher, thank goodness, said no.